Barclays is braced for a bill of more than £2billion after increasing the amount of money set aside to settle a foreign exchange rate-rigging investigation.

The banking giant made another £800million in provisions in relation to the scandal, which has already resulted in six other lenders being fined £2.6bn by global regulators.

Barclays has also taken an additional £150m towards redress for the mis-selling of payment protection insurance (PPI), lifting its total provision for the long-running case to £943m.

The items overshadowed the latest results from the bank after it posted a 9% increase in pre-tax profits to £1.85 billion for the first quarter of the year.

Chief executive Antony Jenkins said: “Resolving legacy conduct issues is an important part of our plan to transform Barclays.

“We are working hard to expedite their settlement and have taken further provisions of £800m this quarter, primarily relating to foreign exchange.

“While we still have much to do, I am pleased with how we’ve begun 2015.”

The bank chose not to enter into settlements last November when other lenders were punished by regulators including the Financial Conduct Authority.

It is seeking a “more general coordinated settlement”, with other authorities in the US still investigating.

Barclays has been reviewing its foreign exchange trading over a period of several years and is continuing to co-operate with relevant bodies. It has warned that these investigations could result in “substantial monetary penalties”, with today’s results taking provisions for potential litigation above £2bn.