A majority of manufacturing exporters believe the falling pound is bad for their businesses despite helping them to increase exports in the last three months at the strongest pace for two and half years.

Almost half, or 47%, cited sterling’s depreciation as having a negative impact, against 32% reporting a positive impact, according to the latest quarterly CBI industrial trends survey.

They warned that uncertainty surrounding the Brexit vote and the UK’s tariff-free access to European Union markets was undermining confidence, while sterling’s rapid depreciation had pushed up import costs and squeezed profit margins.

The number of jobs in the sector is also likely to fall after the survey found that a balance of 15% of manufacturers expect to cut employment over the coming quarter, which is the weakest reading for seven years.

The mixed picture was described by the CBI, which represents Britain’s largest employers, as a reaction to uncertainty in the aftermath of the referendum.

Chief economist Rain Newton-Smith said businesses were wary of Britain closing its borders to skilled workers from the European Union and failing to win barrier-free access to EU markets, despite taking the opportunity to boost exports after the pound’s 18% fall against the dollar.

She said import costs were also proving a headache and could soon lead to rising prices, limiting the potential export gains.

The government is under pressure to clarify its stance on Europe and give details of a new industrial strategy. Philip Hammond is due to outline how ministers will support business growth next month in his autumn statement following a pledge by Theresa May for a switch away from the laissez faire policies of her predecessor to more active management of the economy.

The EEF, which represents manufacturers, said on Monday it was concerned the Treasury was moving slowly and could miss an opportunity to support the sector’s “ambitious growth plans”.

Newton-Smith said: “Manufacturers are optimistic about export prospects and export orders are growing, following the fall in sterling.

“However, the weaker pound is also feeding through to costs, which are rising briskly and may well spill over into higher consumer prices in the months ahead.

“Access to skills clearly remains a high priority, so manufacturers will be looking to the government to implement a new migration system that meets the needs of business while responding to clearly stated public concerns. Maintaining a preferential route between the UK and the EU, our largest trading partner, will be important.”

The survey of 459 manufacturers found that sterling’s fall meant the UK’s competitiveness in EU markets rose at the fastest pace since the survey began in 2000, with competitiveness outside the bloc also improving at the quickest rate since 2009.

But the UK’s improved position failed to halt a decline in optimism about the more general business situation, which fell for the second consecutive quarter, albeit more slowly than the previous sharp decline.