(Reuters) - HSBC Holdings Plc has set aside $550 million more to cover potential fines for alleged manipulation of foreign exchange markets and warned it could face a $500 million bill to compensate U.S. customers sold debt protection products.

HSBC said in its annual report on Monday it had paid restitution to some U.S. customers in connection to debt protection and other products offered before May 2012.

It said additional remediation for this issue "may lie in a range from zero to an amount up to $500 million."

HSBC paid $611 million to U.S. and UK authorities in November when it was one of six banks fined for alleged manipulation of FX markets.

U.S., UK and other authorities are still investigating the issue and the bank had $550 million provisioned at the end of December, its annual report said.