President Dmitry Medvedev has signed a decree toughening sanctions on Libya five months after the measure was passed by the UN Security Council in March, the Kremlin said Friday.

It was not immediately clear why Medvedev signed the decree implementing the sanctions so long after Resolution 1973 was passed.

Russia was obliged to sign the measure as a member of the UN Security Council, and Medvedev's decree makes no mention of the foreign military action specified in the measure.

The measures approved by Medvedev include a ban on the use of Russian airspace by Libyan planes or non-humanitarian flights to Libya.

The decree also slaps an asset freeze on Moamer Kadhafi, his close relatives and entourage, and forbids them from travelling to Russia.

Russia had abstained from the vote on the resolution, while not using its right to veto, out of concerns that the establishment of a no-fly zone within Libya would open the way to a full-scale military operation.

The March 17 resolution slammed Libya for failing to comply with an earlier resolution adopted in February and called for a no-fly zone and protection of rebels from Kadhafi's forces.

Medvedev had in March signed a decree implementing Resolution 1970 adopted in February, which Russia backed.

That measure banned all weapons sales and required the careful inspection of cargo bound to or arriving from Libya.

Russia was a key arms supplier to Libya before the international air campaign began and still has an embassy open in Tripoli, although it has now joined international calls for Kadhafi to step down.