It said one of the men, Zaur Dadayev, had admitted involvement in the shooting on a bridge near the Kremlin on 27 February.

He and the other accused, Anzor Gubashev, are of Chechen origin.

Three other suspects were remanded in custody. A sixth man is reported to have killed himself in a standoff with police in the Chechen capital Grozny.

The suspect threw one grenade at the arresting officers and blew himself up with another, a security source told Interfax news agency.

Younger brother

Nemtsov, a former deputy prime minister and veteran liberal politician, 55, was shot in the back four times as he was walking with his girlfriend within sight of the Kremlin. He was buried in Moscow on Tuesday.

Anzor Gubashev and Mr Dadayev, who are both accused of organising and carrying out the murder, were brought into court amid heavy security.

Little is known about the men, but reports say Mr Dadayev once served in a battalion of interior ministry troops in Chechnya.

The other suspects include Mr Gubashev's younger brother Shagid Gubashev and two men named as Ramzan Bakhayev and Tamerlan Eskerkhanov. Reports say all three have denied any involvement in the murder.

Four of the men come from the northern Caucasus region and were detained in the republic of Ingushetia which borders Chechnya, say Russian media reports.

(BBC)