The Guardian newspaper reported on Saturday that spy agencies in Germany, France, Spain and Sweden were carrying out mass online surveillance and wiretapping.
The organizations were working in collaboration with Britain, according to documents the paper said had been obtained from US whistle-blower Edward Snowden.
Britain's electronic surveillance center GCHQ was reported to play a leading role in helping countries across the continent to circumvent laws that limit spying activities.
The report said that Europe's intelligence services had forged a "loose but growing alliance," carrying out surveillance of fiber-optic cables.
In its report, the Guardian Saturday quoted a 2008 survey conducted by GCHQ of its partners.
The British report said that Germany was tapping fiber-optic cables, adding that Germany's external intelligence agency the BND had "huge technological potential and good access to the heart of the Internet."
GCHQ had identified an opportunity to help the BND expand its operations by finding ways to circumvent or change "very restrictive" laws that affected it, the report said.
'Technological tips, not legal ones'
While the BND confirmed that it shared information, it said the exchange of information was about technological rather than legal issues.
"It is not true that the Federal Intelligence Agency allegedly tried to circumvent legal restrictions in order to use British surveillance technology," said BND spokesman Martin Heinemann. BND refers to the agency's German name, Bundesnachrichtendienst.
"A regular exchange of information about technological developments takes place with other European agencies," said Heinemann.
The report could prove embarrassing for the governments of Germany and France, which have been particularly vocal in their criticism of the US National Security Agency (NSA).
Reports that the NSA spied on the cell phone of German Chancellor Angela Merkel have surfaced in the past fortnight. The US is also accused of collecting data about the phone calls of millions of European citizens and carrying out vast online trawling operations.
Data protection is a particularly sensitive issue in Germany, given its history of totalitarian intrusion under the Nazi regime and the subsequent communist era in East Germany.
Germany and the US were reported to have struck a two-way deal not to spy on each other, a German newspaper reported on Saturday.
A delegation of officials from Merkel's office and German intelligence officials reached agreement during talks at the White House, the Frankfurter Allgemeine Sonntagszeitung (FAS) said.
rc/hc (AFP, Reuters, dpa, AP)