Spies from Germany and the U.K. have been engaging in covert operations to help Syria's rebel forces topple President Bashar al-Assad's regime, according to reports from the British and German press, just as U.N. observers end a failed mission to monitor the violence.

A German navy vessel off the coast of Syria has been providing rebels within the country information about the location of forces loyal to Assad, according to Germany's Bild am Sonntag newspaper. The ship is equipped with gear that allows it to observe Syrian troops moving up to 375 miles inland. The information gathered is passed along to rebel troops via conduits in U.S. and British intelligence services, according to Bild.

"We can be proud of the significant contribution we are making to the fall of the Assad regime," an official from Germany's BND foreign intelligence service reportedly told the paper.

The newspapers' reports also said German intelligence agents stationed in an active NATO base in nearby Adana, Turkey, were monitoring phone calls and radio communications in Syria. The British were reportedly passing along intelligence information gathered from posts in nearby Cyprus, according to the Sunday Times newspaper, with a particular focus on troop movements around the commercial epicenter of Aleppo, scene of fierce battles in recent weeks.

Germany's Defense Ministry admitted that a reconnaissance ship was stationed in a harbor in Sardinia, Italy, but did not give details as to what work it was doing. Britain's Foreign Office similarly demurred, with a spokeswoman simply stating Britain was giving Syria's rebels non-lethal support.

Assad has been in the throes of a 17-month uprising, in a civil war that has escalated to include 137 deaths on Saturday, and counts members of his inner circle among the estimated 23,000 dead. The West has demanded Assad's resignation as part of any deal to end the fighting, though it has faced headwinds from the regime's reliable allies in Moscow and Beijing.