LONDON (AFP) - British bank Barclays has lost "tens of millions" of dollars after Switzerland's central bank scrapped its currency ceiling against the euro, a source with knowledge of the issue said Friday.

Barclays, which lost 1.58 per cent Friday on London's FTSE 100, declined to comment on the information from the source, who spoke on condition of anonymity.

The Wall Street Journal reported, meanwhile, that Deutsche Bank has also lost around US$150 million (S$199 million) on the foreign exchange markets due to the move, although the German bank did not confirm this.

Switzerland's central bank has come under fire at home and abroad after scrapping efforts Thursday to stop the overheated franc rising.

Shares on the country's main SMI index fell 5.96 per cent Friday, a day after plunging 8.7 per cent in the steepest fall since 1988.

Currency broker Alpari UK declared insolvency on Friday after clients' losses were passed on to the company, while shares in leading foreign-exchange broker FXCM were suspended as trade opened in New York as the company was reportedly seeking a cash lifeline.