'Friends don't bug each others telephones' - the view of the Tánaiste over the on-going bugging of phones by United States authorities.

Eamon Gilmore says it is not appropriate for the US to be spying on Ireland or any other European state. It comes amid reports that US intelligence chiefs monitored the phone of German Chancellor Angela Merkel for over ten years.

It is also claimed they may have spied on millions of phone calls in Spain and France.

Mr. Gilmore says he has told the US that what is not clear is what answer, if any, he was given.

US intelligence chiefs have meanwhile defended listening-in to the phone calls of world leaders.

National Intelligence Director James Clapper said earlier this week that all intelligence operations are essential to homeland security.

At the hearing, Mr. Clapper explained why monitoring goes on "For one, to determine, from an intelligence perspective, if what they're saying really gels with what's going on. It's invaluable for us to know where countries are coming from, what's going on, how that would impact us across a whole range of issues."

And he says that includes trying to understand the intentions of foreign leaders.

But Mr. Clapper said the media had gotten it wrong on reports they had read about millions of calls listened to in France and Spain which, he said, actually related to information the US had been given through its collaboration with European agencies.

He alleged reporters had misinterpreted the data they were leaked.