European Commission chief Jean-Claude Juncker wrote to Russian President Vladimir Putin this week, suggesting closer trade ties between the EU and a Russian-led economic bloc once a ceasefire is implemented in Ukraine, but the Kremlin dismissed the idea.

In the letter, written after a G20 summit in Turkey, Juncker underlined the importance he attached to good relations between the European Union and Moscow, "which to my regret have not been able to develop over the past year".

He said he had asked Commission officials to study options to bring the EU and the Eurasian Economic Union -- a grouping of former Soviet states dominated by Moscow -- closer together.

"The decision on the circumstances in which to proceed along this path is in the hands of the member states of the European Union and should in particular be synchronized with the implementing of the Minsk agreements," Juncker wrote, referring to the name of a peace deal relating to Ukraine.

The initiative could offer Putin an incentive to cooperate in Ukraine at a time when France and some other west European states are trying to re-engage with Moscow after the Paris attacks to fight Islamic State and forge a peace deal in Syria.

The Kremlin reacted coolly, saying on Thursday it had received the letter, but that what Juncker was proposing was unrealistic.

"This correlation with fulfilling the Minsk accords, especially in the current conditions when we see Kiev's unwillingness once again to honor these accords is hardly relevant or possible," Putin's spokesman Dmitry Peskov told reporters.

The idea of dialogue between the EU and the Eurasian Economic Union was an old one, Peskov said, but one which he conceded was essential to develop trade and economic relations.

Lithuanian Foreign Minister Linas Linkevicius said he was surprised by the letter, which he said did not reflect a common view of EU member states and made no reference to EU sanctions against Russia over its annexation of Crimea and the destabilization of eastern Ukraine.

Baltic and central European member states are worried that the EU executive and west European partners may be preparing to let Moscow off the hook of sanctions over Ukraine in return for cooperation in the Middle East.

A Commission spokeswoman confirmed that Juncker had written to Putin after they had a brief conversation at the G20 summit but said he had not made any new commitments in the letter.

Juncker caused controversy last month when he said at an event in Germany that Europe must improve its relationship with Russia and should not let this be decided by Washington.

"We must make efforts towards a practical relationship with Russia," he said on 8 October in Passau. "It's not sexy but that must be the case, we can't go on like this."

The Eurasian Economic Union is a newly-formed trade bloc which, aside from Russia, includes Armenia, Belarus, Kazakhstan and Kyrgyzstan.

EU officials said nothing in Juncker's letter called into question the extension of the financial and personal sanctions against Russia when they come up for renewal in January.

Linkevicius said he was confident that there would be agreement to roll over the measures in January.

"I would prefer an improvement of the situation in Ukraine, but all indications at the moment show that the Minsk agreements are not kept. And our agreement is that in such case we will extend sanctions," he said.

Concluding the brief letter, Juncker said he had asked his diplomatic adviser, Richard Szostak, to follow the issue of closer trade ties closely.

"I can assure you that the European Commission will be a helpful partner in this process," he wrote.

Russia seized Crimea militarily last year after pro-Moscow Ukrainian President Viktor Yanukovich was ousted by a popular uprising in favor of closer economic and political ties with the European Union.

The EU has imposed successive waves of sanctions over the annexation of the Black Sea peninsula and support for separatist rebels in Eastern Europe.