The Independent newspaper said on Thursday it was not disclosing the country where the base is located, but said the facility can intercept emails, telephone calls and web traffic for the US and other intelligence agencies.

The British base taps into underwater fibre-optic cables in the region, the newspaper said.

It passes the information back to the British electronic eavesdropping agency GCHQ (Government Communications Headquarters), in Cheltenham, southwest England, which then shares it with the US National Security Agency (NSA).

Britain's Foreign Office said when contacted by AFP about the report that "we do not comment on intelligence matters".

The Independent did not say how it obtained the details from the Snowden files.

Snowden, a former NSA contractor, first released details of US and British surveillance activities through the Guardian newspaper earlier this year. Russia has granted him temporary asylum as he bids to avoid prosecution in the United States.