BRUSSELS (AFP) - France and Germany want talks to agree new rules for intelligence relations with the United States by the end of the year after US eavesdropping on German Chancellor Angela Merkel's mobile, the EU announced on Friday.

The leaders of the 28-state European Union "took note of the intention of France and Germany to seek bilateral talks with the United States" on what their secret services should and cannot do, EU President Herman Van Rompuy told a press conference after a first night of summit talks.

The demand from Berlin and Paris, on the back of anger in Brazil and Mexico at agents listening in on their leaders' calls too, comes "with the aim of finding before the end of the year an understanding on mutual relations in that field".

Van Rompuy said other countries could participate alongside Berlin and Paris should they wish, and underlined that British Prime Minister David Cameron "agreed with the text as it stands".

He added: "Of course the UK has a special relationship ... but they are completely on board."

Citing "deep concern among European citizens" after fresh newspaper revelations in Britain claiming 35 international leaders had private calls monitored like Merkel, Van Rompuy said that intelligence-gathering remains a vital element in the fight against terrorism.

Italian Prime Minister Enrico Letta denied tensions with Britain amid reports of intra-EU espionage - Cameron exiting the summit venue without speaking to waiting media.

But Van Rompuy stressed that the new understanding the Europeans want "applies to relations between European countries as well as to relations with the US".

He underlined: "A lack of trust could jeopardise the necessary cooperation in the field of intelligence gathering." Partnership with Washington "must be based on respect and trust - including as concerns the work and cooperation of secret services".

French President Francois Hollande told reporters that a special European cell was already set up to deal with a wave of disclosures concerning America's ultra-secret National Security Agency from fugitive ex-intelligence contractor Edward Snowden.

These experts have to "accelerate their work with our American allies", Hollande said, because "this is a subject which is not going away.

"We know there will be more revelations," he signalled.

Merkel meanwhile told a separate press conference that she did not agree with suggestions the EU should suspend flagship free-trade talks with Washington as a penalty for the intelligence breach of trust.

"When you leave the room, you have to work out how to get back," Merkel said of the dangers that could pose.