David Cameron has set himself the “firm aim” of keeping Britain in the European Union after running a referendum campaign that will focus on the risky consequences of a British exit, according to a leaked document of the prime minister’s negotiations.

In the first authoritative account of his private thinking, the diplomatic note suggests Cameron has formulated a relatively modest reform package to secure agreement among fellow EU leaders.

The leaked account of a private meeting between the prime minister and a fellow EU leader states: “He believes that people will ultimately vote for the status quo if the alternatives can be made to appear risky.”

The revelation is likely to prompt claims that Cameron is planning to repeat the tactics of the pro-UK Better Together campaign, whose warnings were dubbed Project Fear, in last year’s Scottish independence referendum campaign.

In a passage likely to be seized on by Eurosceptics, the note says he told his counterpart that his “firm aim was to was to keep the UK in the EU”, highlighting the country’s importance in areas including foreign policy and defence.

The leaked document, seen by the Guardian, confirms that he would like to hold the referendum next year, ahead of his self-imposed deadline of December 2017.

The prime minister suggested “Angela and Matteo”, referring to the German chancellor and the Italian prime minister, had responded positively to his proposals.

The note shows that the prime minister has tailored his demands, which appear to be relatively compact, in an effort to secure the support of EU leaders.

It says: “The PM said that he had deliberately not produced a lengthy shopping list and had been careful in formulating his wish list, but he needed to get satisfaction on these reform demands.

“He said that he needed to win the middle ground and, if he is to achieve this, then moderate people needed to feel that the things that bother them about the EU have been dealt with.”

The note emerged after Cameron briefed fellow EU leaders at their summit in Brussels on his plans for renegotiating Britain’s role within the EU.

He spoke for about five minutes late on Thursday night after Donald Tusk, the European council president, interrupted an acrimonious discussion about migration to allow him to outline his proposed reforms in the formal setting of a summit.

One diplomat described the prime minister’s intervention as a commercial break.

British and EU officials will hold technical discussions over the summer and into the autumn before the EU’s 28 leaders discuss the reform package at their end-of-year summit in December.

The note confirms that Cameron has abandoned plans to introduce an emergency brake on migration that would have allowed the UK to restrict access for migrants if their numbers reach a certain level.

The prime minister had hoped to set out plans for an emergency brake in his speech on EU migrant reform last November, but he watered down his plan after Merkel said it would risk breaching EUrules on the free movement of people.

The note gives details of the four key areas where he Cameron is seeking change. They are:

• Answering Britain’s concerns about sovereignty by giving the UK an exemption from the EU’s historic commitment to forge an “ever closer union”. The prime minister said the UK did not want to stop other member states from pursuing this goal, but that Britain needed an opt-out because the European Court of justice has used it to push through integrationist measures.

He also suggested giving national parliaments the ability to club together to use yellow or red cards to block EU proposals they object to.

• A renewed focus on competitiveness and economic growth by freeing up the service sector and promoting trade, including the EU-US transatlantic free trade agreement, which is the subject of lengthy and intense negotiations.

• Ensure fairness between eurozone and non-eurozone members to ensure that countries outside the single currency do not have new rules in the single market imposed on them. He cited financial services and the example of the double majority system on banking union. This ensures that new rules have to be agreed by a majority of eurozone and non-eurozone countries.

• Imposing restrictions on EU migrants claiming benefits. He had hoped to introduce an emergency brake but now accepts this is not possible. Cameron has been accused of planning to act in a discriminatory way after he proposed imposing a four-year ban on EU migrants claiming in-work benefits.

The prime minister said it was not fair to talk about discrimination and it was not unreasonable to ask immigrants to wait to claim welfare benefits. According to the note, Cameron said Denmark and the Netherlands were sympathetic to this view.

The note also shows that he may be prepared to tone down his call earlier this year for some of his reforms to be embedded in “full-on treaty change”. He says that he needs legal certainty, but that he might be prepared to settle for a protocol “to change the treaties in due course”.

In his discussion with his fellow EU leaders, highlighted in the note, the prime minister indicated that he had concerns that the no campaign would be well funded by business. Cameron said the EU would need to make itself more business friendly in order to help him counter such a campaign.

The document suggested he had said: “In 1975, 100% of business people were in favour of EU membership, but that is no longer the case. On the occasion, the no campaign will be well-funded by business people with an anti-EU outlook.”

Asked about the leaked note at a press conference in Brussels on Friday, Cameron insisted he was adopting a positive and optimistic vision of Britain’s EU membership.

He said: “My view is a wholly positive view, which is that I am making positive arguments about how Britain’s relationships should change, about how Europe should change so that I can make a positive argument about Britain staying in a reformed EU. I have always said if I don’t succeed in that I rule nothing out. Let me repeat that again today.”

The prime minister mocked Nigel Farage after the Ukip leader said that the leaked document showed that the prime minister’s EU renegotiation was a “complete con job”.

Cameron said: “As for Nigel Farage, I don’t remember him being in any of these meetings, but as this man can miraculously resign and un-resign, maybe he was there in some corporeal form.”

Cameron told reporters that his tour of EU capitals before the summit had been a success as he highlighted the need to secure protections for non-eurozone countries.

He said: “I would say that the tour of European capitals, the conversations I have had with other prime ministers and presidents, has gone well. There is a lot of hard work to do. Some of these things will be very tough to achieve. But people can see that Britain has a legitimate set of questions, a legitimate set of asks. People can see there is also really deep and sensible thinking behind this.”

Downing Street is likely to argue that the prime minister made clear in his Bloomberg speech in January 2013, in which he first set out his plans to hold a referendum, that he wanted Britain to remain in the EU. He said then that the UK should play a “committed and active part” in a reformed union.

Cameron also made clear that there would be consequences of leaving the EU, which he described as a “one-way ticket, not a return”. He said an exit would have an impact on Britain’s access to the single market and on its standing in the world.