European Union officials head into complex security talks in Washington on Monday threatening to suspend key data-swapping deals with the United States amid continuing anger over reports of US snooping.

Brussels this week warned Washington in a letter obtained by AFP that it was ready "to reconsider" two key anti-terrorist data-sharing deals failing US assurances of their "full compliance with the law".

The warning over hard-won agreements to share airline passenger data and SWIFT banking details as part of the global fight against terrorism comes amid public outrage over reports that US agencies spied on Europeans as well as on their institutions and embassies.

"We are experiencing a delicate moment in our relations with the US," the EU's

Home Affairs Commissioner Cecilia Malmstroem said in a letter to Homeland Security Secretary Janet Napolitano.

"Mutual trust and confidence have been seriously eroded and I expect the US to do all that it can to restore them.11

Malmstroem said her staff would be in Washington next week for the first review of the 2012 Passenger Name Record (PNR) agreement - enabling the transfer of EU air passenger data to US authorities - as well as a review of the older Terrorist Financing Tracking Program ( TFTP), which accesses the SWIFT global interbank transfer network.

Ties between Washington and Brussels have been strained since Edward Snowden, a former contractor with the National Security Agency (NSA), revealed that the US was systematically seizing vast amounts of Internet and telephone data around the world.