Russia must solve U.S. reporter's murder: family

MOSCOW (Reuters) - The family of murdered U.S. reporter Paul Klebnikov said on Tuesday they were deeply disappointed that Russian authorities had failed to catch his killers and urged them to improve their efforts.

Around 100 people -- including the U.S. ambassador to Russia -- gathered at a crumbling church in central Moscow for a memorial service four years after gunmen shot Klebnikov as he left his office.

Klebnikov, who edited the Russian edition of Forbes business magazine and investigated Russia's rich and famous, died of his injuries a few hours later in a hospital lift which broke down.

"Paul's assailants and the masterminds behind this terrible crime have yet to be brought to justice. We are deeply disappointed by this lack of results," the Klebnikov family said in a statement.

U.S. ambassador John Beyrle, at one of his first public events since taking up his post on July 3, declined to make a statement at the end of the hour-long service,

"My presence is comment enough," he said.

Klebnikov's killers and those who ordered his death have yet to be found. The trial of two Chechens who prosecutors said had executed the murder collapsed in 2007 when a jury acquitted them.

Russian President Dmitry Medvedev has said he wants police to track down and catch the killers of journalists more quickly.

Last month prosecutors charged three men with a role in the murder of investigative reporter Anna Politkovskaya, killed by gunmen in 2006.

(Reporting by James Kilner)