MOSCOW, August 10 (RIA Novosti) - Lawyers acting for a Russian military intelligence colonel sentenced to 13 years in prison for spying for the United Kingdom have filed an appeal, a spokesman for the Moscow district military court said Thursday.

The Federal Security Service (FSB) said retired officer Sergei Skripal, 55, who was convicted Wednesday of "treason in the form of espionage", had been recruited by the Secret Intelligence Service, better known as MI6.

"Attorney Yelena Lebedeva-Romanova has filed an appeal with the military board of the Supreme Court," court spokesman Yevgeny Komissarov said.

The FSB said Wednesday that Skripal had admitted his guilt and gave truthful testimony about his activities, which the court had taken into consideration.

"The investigation into the case ... established that during his service in the Russian Armed Forces in the mid-1990s, Skripal was recruited by British intelligence and shared state secrets with it," the FSB said in a news release.

Russia's respected daily Izvestia said Skripal had shared information about dozens of his former colleagues operating in Europe under cover, in particular, their secret meeting venues, addresses and passwords.

Komissarov said Skripal had received at least a total of $100,000 for his collaboration.

Chief Military Prosecutor Sergei Fridinsky said he was satisfied with the verdict, adding that Skripal would serve his sentence in a high-security penal colony.

Fridinsky said he had asked the court to sentence Skripal to 15 years, but the court had taken into account mitigating circumstances such as the convict's admission of guilt, assistance to the investigation and poor health.

Izvestia said Skripal had been arrested in December 2004 on treason charges. The investigation lasted a year and a half. The case was submitted to court in late June 2006, and the lawsuit continued for more than a month.

A major spying scandal clouded relations between Russia and the U.K. at the start of the year, when Moscow claimed four British agents in the Russian capital had been caught procuring information from a high-tech communication device disguised as a rock.