Russian investigators on Friday formally charged an ex-defence minister with negligence and did not rule out expanding the charges following a further investigation.

Anatoly Serdyukov, who was fired a year ago in a major corruption scandal, has been charged with negligence for using servicemen to build a road to a private residence in southern Russia, the Investigative Committee said.

The former defence minister faces up to three months in prison or up to a year of "corrective work" or community service if convicted of the charge.

"I would like to specify that this is just an initial charge," spokesman for the Investigative Committee, Vladimir Markin, said in a statement.

He did not rule out that the charges would be expanded following a further investigation.

The once influential official is accused of ordering servicemen to refurbish a private holiday residence on an island in Russia's southern Astrakhan region and to build a road to it. The investigation estimates the damages to the state at 56 million rubles ($1.6 million).

The holiday residence belonged at the time to Serdyukov's son-in-law.

Serdyukov did not admit guilt and refused to testify against himself, the Investigation Committee said Friday.

Investigators first announced they were bringing criminal charges against the former minister last week.