The boss of the revived British Steel has claimed that Tata Steel “lost interest” in the Scunthorpe steelworks, one of only two left in Britain, and that the site is back in profit just three months after it was sold by the Indian company.

Roland Junck, executive chairman of British Steel, said the Scunthorpe steelworks had become “inward-looking” and “stopped comparing themselves with the best”.

British Steel was re-formed in June when investment firm Greybull bought Tata Steel’s long products business, which is primarily the Scunthorpe steelworks, for £1 and renamed it. British Steel disappeared in 1999 when it merged with a Dutch rival to become Corus. Corus was later bought by Tata Steel.

Tata Steel offloaded the Scunthorpe site earlier this year as it battled to stop mounting losses in its UK business. The Indian company is still considering the future of Port Talbot, the only other steelworks with blast furnaces in Britain.

However, Junck, the former chief executive of ArcelorMittal, said the long products business is back in profit at an underlying level – before financing costs – and that the new owners’ financial plan is on track. He is targeting a 10% profit margin on its annual revenues of £1.2bn, meaning it could eventually make a profit of £120m a year.

“It has gone from making several millions of pounds of losses a month to positive financial results month-on-month,” he said at an event in Scunthorpe to mark 100 days since the new company was formed. “We are exactly on track so far and expect to meet our financial targets in this fiscal year.”

British Steel has focused on controlling costs and rebuilding its relationship with customers, which include Network Rail, Toyota, and Transport for London. The company supplies rail for train tracks, high-strength wire-rods for deepwater mooring and steel for construction projects such as the Shard in London and the new stand at Liverpool’s football stadium Anfield.

It plans to invest £50m into modernising facilities this year and one of its first acts was to ask staff to take a 3% pay cut, which they agreed.

“The former owner at some point lost interest in these activities,” Junck said of British Steel’s plan. “When you understand what good looks like you see significant differences. One of the big weaknesses was they had seemingly years ago stopped comparing themselves with the best ones.”

British Steel employs 4,800 people, including 400 in France, and produces more than 2.8m tonnes of steel a year. The Scunthorpe steelworks is one of the biggest industrial sites in the country. Its perimeter is 15 miles long and more than 100 miles of railway exist inside to transport materials.

Junck said Britain could still have a sustainable steel industry but that it would need to be specialised and not based on scale. “For this size, for this product, for this kind of market, yes I see a sustainable future,” he said. “But this is why the UK does not produce 200m tonnes of steel anymore.”

He called on the government to do more to help the industry. “The transformation of our business will make sure we maintain the pace of growth and move forward as an outward-looking profit-making business. But while our future remains firmly in our hands, the UK steel industry still faces many challenges,” Junck said.

“That is why we are pleased to remain in constructive dialogue with the government about the strategy needed to support British Steel and ensure that it is operating on a level playing field. It goes without saying that any strategy must be long-term and cross all political divides if it is to achieve the goals we share.”

Junck said the implications of Britain’s vote to leave the European Union were “still unclear” but that it had “not made things easier”.

The British Steel management team and the workers expressed their support for Greybull, the owners, despite other businesses it controls running into trouble. My Local, the convenience store business, has collapsed while the future of Monarch, the low-cost airline, is also in doubt.

Paul McBean, the trade union chairman of the Scunthorpe steelworks, said he had been impressed by the investment firm in talks before and after it bought the business. “Do I still have faith in our investors? Yes I do,” he said.