Kyiv has welcomed reported Chinese comments criticising threats to use nuclear weapons, with Russia’s invasion of Ukraine in the spotlight as world leaders gather in Indonesia for the G20 meeting.

US President Joe Biden and Chinese President Xi Jinping “underscored their opposition to the use or threat of use of nuclear weapons in Ukraine”, the White House said in a readout of a meeting in Indonesia between the two leaders on the eve of the summit.

A readout of the Biden-Xi meeting on China’s foreign ministry website made no use of the word “nuclear” but said “conflicts and wars produce no winner … and … confrontation between major countries must be avoided”.

Russian President Vladimir Putin has repeatedly suggested Russia could use nuclear weapons to defend its territorial integrity, interpreted in the West as an implicit threat to use them over lands Moscow claims to have annexed.

Mr Xi and Mr Putin have grown close in recent years, bound by their shared distrust of the West. China has refrained from publicly criticising Russia for the invasion Ukraine or from calling on it to withdraw its troops.

Ukraine President Volodymyr Zelensky, who had earlier visited Kherson, the biggest prize his troops have recaptured since the invasion began in February, welcomed Monday’s remarks.

“It is important that the United States and China jointly highlighted that the threats of using nuclear weapons were unacceptable,” Mr Zelensky said in a late Monday address.

“Everyone understands to whom these words are addressed.”

Mr Zelensky will speak to the G20 summit via video link on Tuesday.

In Turkey, US and Russian spy chiefs met in the first known high-level, face-to-face contact between the two countries since the war in Ukraine began.

To help avoid conflict escalation, CIA director William Burns met on Monday with Russian foreign intelligence chief Sergei Naryshkin to convey the consequences should Mr Putin use nuclear weapons, a White House spokesperson said.

The Kremlin confirmed a US-Russia meeting had taken place in Ankara but declined to give details.

“The Ukrainian side views these talks with a maximum of realism,” Ukrainian presidential adviser Oleksiy Arestovych said in an online video.

Ukraine celebrates major win

Earlier on Monday in Kherson, Mr Zelensky shook hands with soldiers and waved to civilians as he was escorted by bodyguards three days after his troops swept into the city.

Kherson city had been the only regional capital captured by Russia since the invasion and Mr Putin had proclaimed it “eternally Russian” six weeks ago.

Ukraine has repeatedly said it is ready for peace but will not cede territory.

“Ukrainian servicemen accept no talks, no agreements or compromise decisions,” Armed Forces of Ukraine Commander-in-Chief Valery Zaluzhny wrote on Telegram late on Monday.

Mr Zelensky said Ukraine had gathered evidence of at least 400 war crimes committed by Russian troops during their occupation of the area, including killings and abductions.

Russia denies its troops target civilians or have committed atrocities.

Mass burial sites have been found in other parts previously occupied by Russian troops, including some with civilian bodies showing signs of torture.

To the north and east of Ukraine, there were reports of fierce clashes and artillery bombardments along the front lines that stretch more than 1000 kilometres.

“The enemy is attempting to hold temporarily occupied territory and is continuing to equip areas on the east bank of the Dnipro River,” Ukraine’s armed forces general staff said in a Facebook post on Monday.

“It is maintaining its offensive actions near Bakhmut and Avdiivka,” the statement added, referring to areas in eastern Donetsk region.

Russia’s defence ministry was quoted by RIA news agency as saying its forces had taken the village of Pavlivka in Donetsk.

Neither sides’ accounts could be independently confirmed.

–AAP