Two industrial unions are offering a bounty for anyone who can locate two private Mitt Romney fundraisers in London.

The United Steelworkers and Unite are offering a dinner for two at an American-style restaurant in London to anyone who can help locate two fundraisers Mitt Romney is hosting are located.

According to the announcement, banking officials are hosting a "highly secretive $25,000 to $75,000 a head fundraising event" for Romney in London on Thursday.

The unions say they want to give Romney two gold medals as rewards: "austerity (for others) and the other for financial secrecy."

"It's no surprise then that Romney is in London for a secretive but lavish fundraising event where bankers and other city elite can continue to back austerity for the 99 per cent while they continue as if it's business as usual," Unite General Secretary Len McCluskey said in a statement. "The fact that the event was to be hosted by disgraced former Barclays CEO Bob Diamond speaks volumes. "

"Romney has earned a reputation as a jobs destroyer, political flip-flopper and tax avoider," said USW International President Leo W. Gerard, "and now he's refusing to disclose his tax returns.

"We feel his commitment to financial secrecy is certainly worthy of the Olympic gold."