President Vladimir Putin said on Wednesday that Russia, facing the threat of new sanctions over the Ukraine crisis, wanted to avoid international isolation but would strongly defend its national interests.

"We will never pursue isolationism. We will always be part of the international community," Putin said during a meeting with representatives of the Civic Chamber, a consultative body which monitors the work of the government and parliament.

"You and I must properly define national interests. We have learnt how to do that," he said. "We will do this persistently but correctly, carefully and ... strongly."

The United States and the European Union have imposed visa bans and asset freezes on some Russian companies and individuals since Russia annexed the Crimea peninsula from Ukraine in April after the overthrow of a Moscow-leaning Ukrainian president.

Washington and Brussels have held out the possibility of more sanctions if pro-Russian separatist fighters do not wind down the conflict in eastern Ukraine.

The rebels in eastern Ukraine have called for military support from Moscow since ceding control of one of their strongholds, the city of Slaviansk, to Ukrainian government forces on Saturday but Putin has not publicly responded.

Russian officials have suggested the sanctions will rebound on the West but, since they were imposed, Putin has withdrawn most of the troops he had massed near the border with Ukraine and has discussed ways to end the crisis with European leaders.

Putin again avoided directly addressing the appeal for help from the rebels at his meeting with the Civic Chamber representatives, calling instead for humanitarian assistance to those affected by the fighting.