The European Parliament should set up an inquiry into the unauthorised interception of telephone calls and e-mails by British and US spying systems, according to the Green Party MEP, Ms Patricia McKenna.
There was evidence that unauthorised surveillance of telecommunications was being carried out by organisations which were completely unaccountable, she claimed.
"It is highly disturbing that the UK should be actively involved in running a spying operation against its own partners," she said.
Ms McKenna was reacting to claims by a British investigative reporter, Duncan Campbell, who told MEPs this week that UK intelligence forces were intercepting all phone calls, faxes and emails out of Ireland.
Monitoring was widespread and carried out without the use of warrants, Mr Campbell told a special hearing of the parliament in Strasbourg.
The system could recognise a voice or key words in an e-mail but could not identify words used in phone conversations, he said.
The claims have been denied by the British government.
The most controversial system, Echelon, was established under an agreement between the US and the UK by the US National Security Agency and Britain's General Communications Headquarters. Originally designed to monitor the communications of Eastern Bloc countries, it is now used for industrial espionage, according to a report prepared for the European Parliament's scientific and technology options assessment panel.
Last year, Mr Campbell claimed British intelligence services had been intercepting telephone calls to and from the Republic since the 1980s.
