Turkey is pushing to revive talks between Russia and Ukraine stalled after atrocities were uncovered in Bucha and other regions near Kyiv, saying the two countries are still ready to meet on its soil.

The positive atmosphere that emerged after the Istanbul talks last week between Russian and Ukrainian negotiators were "overshadowed" by "shameful" images from Bucha, Foreign Minister Mevlut Cavusoglu said on Thursday.

Ankara assures that the two warring sides are still "willing to hold talks" in Turkey in a bid to move towards a solution to the six-weeks war.

"Both Russia and Ukraine are willing to hold the talks in Turkey but they are far away from agreeing on a common text," a high-ranking Turkish official told a small group of journalists on Friday.

There are "some issues pending" including the status of the Donbas and Crimea regions as well as security guarantees, according to the official, who added there was no date fixed for the next round of negotiations.

Turkey, which hosted talks last week between Russian and Ukrainian negotiators, has been mediating for an end to the conflict.

"We are the only country that can talk to both parties, the only country able to talk to Russia," the official stressed.

"We are not proposing anything but we are trying to facilitate what they are discussing."

Turkey has strong ties with both Russia and Ukraine. As a NATO member, it has supplied Kyiv with drones but has shied away from joining Western sanctions against Moscow.

"Imposing sanctions is not a good way to solve the issue," the Turkish official said, adding that Ankara would only join UN sanctions.

The official said the most delicate issues were discussed in Istanbul between the two countries' negotiators, without providing any details.

After the negotiators met in Istanbul on March 29, President Recep Tayyip Erdogan placed phone calls to Russian leader Vladimir Putin and Ukrainian counterpart Volodmyr Zelensky, renewing his invitation to host a leaders' summit.

TTurkish President Recep Tayyip Erdogan opening Ukrainian-Russian talks in Istanbul last week
TTurkish President Recep Tayyip Erdogan opening Ukrainian-Russian talks in Istanbul last week TURKISH PRESIDENTIAL PRESS SERVICE via AFP / Murat CETIN MUHURDAR

A senior Western source referred to the existence of a "peace treaty" being negotiated between Moscow and Kyiv where the status of the Donbas and Crimea regions remain to be defined.

The Turkish official close to the talks said: "We have some ideas about the content but is it a peace treaty? We cannot qualify the document."

According to the Turkish official, the two countries have "agreed on some issues" including the so-called de-Nazification, Ukraine's neutrality and security guarantees.

But they have to define the security guarantees because some countries "are concerned this could lead to direct confrontation with Russia," the official said.

"There are some legal issues to be solved as part of guarantors."

At the earlier peace talks in Istanbul, Ukrainian negotiators said Kyiv was ready to accept neutrality in return for security guarantees to be provided by the five permanent members of the UN Security Council as well as some other countries including Turkey, Germany, Canada and Israel.

Ukrainian negotiators have compared the security guarantees they want to the NATO treaty's Article 5 where members agree to come to the defence of one another in case of military aggression.

For its part, Moscow has demanded "the unanimity of all guarantors" for any decision, according to the Western source, deeming it "unacceptable" for Kyiv because with Russia holding the veto-power the same as in the UN Security Council.

Turkey has stepped up diplomacy from the first days of the war -- and even before, when the crisis was brewing, with Erdogan offering good offices without alienating Russia, according to the Turkish official.

Russian and Ukrainian foreign ministers also met in southern Turkish province of Antalya in March, ahead of the technical negotiations in Istanbul.

On March 31, Foreign Minister Mevlut Cavusoglu had said the Russian and Ukrainian foreign ministers could meet within two weeks.

But while Russia had pledged in Istanbul to scale down its military activity on the ground, the images that emerged from Bucha last weekend and a fatal rocket attack on Friday on a train station in the eastern Ukrainian city of Kramatorsk have cast a shadow on the peace talks, according to the Turkish government.

An official cited an ancient proverb, saying: "If you go to bed with a Russian, don't forget your knife."