Russian and Ukrainian negotiators will resume face-to-face talks very shortly in Istanbul, according to a Russian presidential aide on Sunday. The striking feature of the talks must be that the Ukrainian President, Volodymyr Zelensky, has said his country is willing to accept neutrality as part of a peace deal.

The holding of the next round of in-person meetings was announced on Sunday by the Russian presidential aide, Vladimir Medinsky, who also leads the Russian delegation to the talks. Russian President Vladimir Putin and his Turkish counterpart Recep Tayyip Erdogan earlier that day spoke over the phone. According to the Turkish presidential office, Mr Erdogan told Mr Putin that his country will continue its mediation efforts in an effort to establish peace between Russia and Ukraine.

“President Erdogan stressed the necessity of reaching a truce and peace between Russia and Ukraine as soon as possible, and of improving the humanitarian situation in the region. He added that Turkey will continue to make its contribution to this process,” Ankara said.

Mr Medinsky wrote on his social network account earlier on Sunday that a regular round of online talks with Ukraine was held, and he confirmed the agreement for officials from the two sides to meet in person on Tuesday and Wednesday. Turkey said the talks could begin as early as Monday, but Kremlin spokesman Dmitry Peskov said that was unlikely as the negotiators would only be arriving on Monday.

President Zelensky spoke optimistically about the new negotiations, saying he hoped they would bring peace “without delay” and lamented the effects of a month-long Russian “special military operation”. Ukraine is ready to accept neutral status as part of a peace deal with Russia, Mr Zelensky said. Any agreement would have to be placed before the Ukrainian people in a referendum, he said. But Mr Zelensky once again stressed his desire to reach a concrete peace agreement.

“Ukraine’s sovereignty and territorial integrity are beyond doubt. Effective security guarantees for our state are mandatory,” he said in a late-night video message that also set out his negotiating bottom lines. He called upon Moscow to halt the bombardment of cities like Mariupol, where officials said the situation is “catastrophic”. Several attempts at establishing safe routes for civilians to flee have collapsed as both sides traded accusations of violating temporary cease-fires.

About 170,000 civilians remain trapped in Mariupol without adequate food, water or medicine, according to Ukraine’s foreign ministry. Russia said the Ukrainian military has been holding the civilians as “hostages” in the southern port city. France, Greece and Turkey hope to launch a “humanitarian operation” to evacuate civilians from Mariupol within days, according to the French President, Emmanuel Macron.

Mr Macron warned on Sunday against a verbal “escalation” of the situation after President Biden called Putin a “butcher” who “cannot remain in power”, a remark the Kremlin snapped back at saying “a head of state should stay sober”.