Russian President Vladimir Putin may hold talks with his Ukrainian counterpart Petro Poroshenko on the sidelines of a summit in Italy next week, his aide said on Thursday.

Putin's top foreign policy adviser Yury Ushakov said the Kremlin was working to put together a meeting that would also include German Chancellor Angela Merkel and French President Francois Hollande.

"A meeting in the 'Normandy format' -- Putin, Merkel, Hollande, Poroshenko -- is not ruled out," Ushakov told Russian news agencies.

The Kremlin "is now involved in this -- possible contacts are being worked out."

Ushakov was referring to a landmark meeting between Putin and Poroshenko on the sidelines of D-Day anniversary ceremonies in Normandy in June, shortly after Poroshenko was elected president on May 25.

The two leaders also met in the Belarussian capital Minsk in August, for one-on-one talks on the fighting in eastern Ukraine.

In Kiev, an official in the Ukrainian presidency did not rule out Poroshenko's participation in the ASEM summit but said it was too early to speak of a bilateral meeting with his Russian counterpart.

A one-month truce in Ukraine is teetering on the verge of collapse as violence in the rebel-held east shows few signs of abating.

Host Italy has said Putin has confirmed his attendance at an Asia-Europe (ASEM) summit in Milan next week, in what will be his first encounter with Western leaders since the Ukraine crisis dramatically deepened this summer.

Italy is hosting the October 16-17 summit as it currently holds the rotating presidency of the European Union.

Also expected at ASEM are Merkel, who normally takes a lead in Western contacts with Putin, British Prime Minister David Cameron and Chinese Prime Minister Li Keqiang, among others.

Some 3,500 people have died since the Ukraine crisis erupted early this year following Russia's annexation of Crimea in March.

In the wake of the crisis, which has roiled Russia's relations with the West, the Kremlin has moved to ramp up cooperation with Asia and Latin America.

Putin's adviser said he is also due to meet Japanese Prime Minister Shinzo Abe on the sidelines of an APEC summit in China in November.

"Putin has received a million invitations to visit various countries including Japan," he added.