BERLIN — Britain's electronic eavesdropping service keeps tabs on foreign diplomats by monitoring their hotel bookings, a German magazine reported Sunday citing leaks provided by former U.S. intelligence contractor Edward Snowden.

News weekly Der Spiegel said that for more than three years, the British Government Communications Headquarters (GCHQ) has had a system to watch reservations at at least 350 upscale hotels around the globe.

"The aim of the program is to inform GCHQ, at the time of the booking, of the city and hotel a foreign diplomat intends to visit," Spiegel said, allowing the "technical operations community" to swing into action before the envoy's arrival.

This can include monitoring a hotel room and its guest by wiretapping the telephone and fax machine, gaining access to computers hooked up to the hotel network, or eavesdropping on the diplomat in the hotel bar, the report said.

The program, given the codename "Royal Concierge" uses a logo with a penguin — meant to stand for the black and white uniforms worn by staff at top hotels — wearing a crown, a purple cape and holding a wand.

Spiegel said it was unclear how often the program had been used. It quoted a GCHQ official as saying the service "neither confirms nor denies the allegation."

Britain's top spy chiefs reacted angrily to leaks by Snowden, a fugitive former analyst for the U.S. National Security Agency, in an appearance this month before a parliamentary committee.

Denying Britons were under mass surveillance, the heads of the foreign spy agency MI6, the domestic intelligence service MI5 and GCHQ warned that al-Qaida and other enemies were "lapping up" intelligence revelations by Snowden and using them to change the way they operate.

The leaks have also strained relations with key partners.

Germany's foreign ministry on Nov. 5 called in Britain's ambassador over a media report that London has been operating a secret listening post from its embassy in Berlin.