PROFITS at payday lender Wonga more than halved last year after it racked up £18.8 million in costs relating to a scandal over fake legal letters.

The company expects it will be "smaller and less profitable" in the near term as it cleans up its reputation in an industry that has been caught up in controversy in recent years.

The profits figure for 2013 slumped by 53 per cent to £39.7 million, even though it issued 4.6 million loans - a rise of 15 per cent - and lent a total of £1.3 billion in the period. The default rate on loans fell to 7 per cent from 7.4 per cent in 2012.

Wonga, which has come under fire from MPs for charging annual interest rates of more than 5,000 per cent, was impacted by higher operating costs and the one-off charge to cover the historic debt collection and system issues.

In June, Wonga was ordered to pay compensation of £2.6 million by the Financial Conduct Authority after sending threatening legal letters from fake law firms to 45,000 customers.

The FCA said Wonga had been guilty of "unfair and misleading debt collection practices" by creating fake companies to pressure struggling customers into paying.

The regulator is bearing down on all providers of short-term credit, proposing in the summer a cap on payday lending meaning that from next January, interest and fees must not exceed 0.8 per cent per day of the amount borrowed.

It also wants to impose a cap on the overall cost of a payday loan so that it cannot exceed 100 per cent of the original sum borrowed. Payday lenders have been attacked by MPs as a form of "legal loan sharking".

Wonga recently appointed Andy Haste, the former chief executive of the RSA insurance group, as chairman in a bid to clean up its battered reputation.

At the time of his appointment, Mr Haste said: "Some serious mistakes have been made.

"The company admitted those mistakes and it has apologised."

Yesterday's figures include a 56 per cent rise in operating costs.