The officer, who cannot be identified, told Michael Cockerell, the maker of a television documentary: "Of course, we are all spying on each other. You need belt and braces, collateral on collateral. It would be as vital to know where your European partners are coming from, as it was to know the order of battle of Soviet forces during the Cold War."
The documentary, How to be Foreign Secretary, is to be shown on BBC 2 on Sunday evening. Its disclosures will come as a shock to pro-Europeans who would never have dreamed that Britain is allegedly involved in espionage within the EU.
During the programme, neither the present Foreign Secretary, Robin Cook, nor his predecessors, denied suggestions that Britain operates a spy network in Europe.
When Mr Cook himself was asked whether Britain received intelligence from her European partners, he replied: "No I'm sorry. I can't talk about that because it is all secret information. We never discuss that."
And Douglas Hurd, now Lord Hurd, who was Foreign Secretary for nearly six years until 1995, was equally reticent. When he was asked the same question, he seemed taken aback. He is shown biting his lip and scratching his thigh. "I don't want to go into that. That's operational. I can't, can't, can't get into that," he said.
Lord Renwick, the former ambassador to Washington, was adamant that the French, for instance, would not spy on Britain. But when he was asked whether Britain would spy on them, he replied: "Ah, that's a separate question. You'll have to ask, er, whoever
He added: "We have intelligence coverage of all really important negotiations ... Sometimes the information is extremely useful - sometimes you know it all already.
William Waldegrave, a Foreign Office minister under the Tories, said: "The Secret Intelligence Service is very useful to the Foreign Secretary. It can't do miracles but it does provide a most extraordinary additional source of good information.
"What you must not do is become James-Bondish about it. And their people are extremely skilful at warning you that not everything that you get on an intercept - or hear on a tape of what some foreign leader said in his bath - is necessarily the full story."Reuse content