Yevgeny Prigozhin, the head of the Wagner mercenary force, offered to reveal the position of Russian troops to the Ukrainian government, the Washington Post has reported, citing leaked US intelligence documents.
Wagner's soldiers have been at the forefront of a bloody Russian offensive to take the city of Bakhmut.
In exchange for Ukraine withdrawing its soldiers from the area, Mr Prigozhin in January offered to tell its intelligence service the positions of Russian forces, the newspaper reported.
The report said Ukraine rejected the offer as Mr Prigozhin was not trusted, with a US official telling the newspaper there were similar doubts in Washington.
The Post said Mr Prigozhin's offer came through his contacts with Ukraine's intelligence service.
A White House spokesman declined to comment on the report, which was based on secret US documents leaked to the group-chat platform Discord.
The leak, the largest of US classified material since a 2013 WikiLeaks release, caused a major headache for US authorities and saw the arrest of a 21-year-old information technology specialist from the Massachusetts Air National Guard.
Mr Prigozhin, a close ally of Russian President Vladimir Putin, has publicly threatened to withdraw his mercenaries from the area around Bakhmut, where they are the vanguard of the Russian offensive, unless they receive much-needed ammunition.
He said in an audio message on Tuesday that he and his men would be regarded as traitors if they abandoned the area.
"A combat order came yesterday which clearly stated that if we leave our positions [in Bakhmut], it will be regarded as treason against the motherland," he said.
"[But] if there is no ammunition, then we will leave our positions and be the ones asking who is really betraying the motherland."
Late last week, the commander of Ukrainian ground forces said Russian troops had fallen back in some regions of the front near Bakhmut by up to 2 kilometres.
"We are seeing the results of the effective actions of our units," Oleksandr Syrskyi said, explaining his forces were launching counterattacks along some portions of the contact line around Bakhmut.
"In some areas of the front, the enemy could not withstand the onslaught of Ukrainian defenders and retreated to a distance of up to 2 kilometres," he added.
Tass news agency cited Kremlin spokesman Dmitry Peskov as saying Russia's military operation against Ukraine was "very difficult" but certain goals had been achieved.
Top Chinese envoy to visit Ukraine, Russia on 'peace' mission
A top Chinese envoy will begin a tour of Ukraine, Russia and other European cities on Monday in a trip Beijing says is aimed at discussing a "political settlement" to the Ukraine crisis.
Li Hui, China's special representative for Eurasian affairs and former ambassador to Russia, will also visit Poland, France and Germany on the multi-day trip, the foreign ministry announced without providing a detailed schedule.
"The visit … is a testament to China's efforts towards promoting peace talks, and fully demonstrates China's firm commitment to peace," foreign ministry spokesperson Wang Wenbin said at a daily briefing.
He is the most senior Chinese official to visit Ukraine since Russia invaded in February 2022, and his trip could coincide with the beginnings of a long-anticipated counteroffensive by Ukraine to recapture territory seized by Russia.
Ukraine is scheduled to be Mr Li's first stop on his trip, according to two sources familiar with the matter.
China's foreign ministry did not reply immediately to a request for comment on the order of the countries Mr Li will visit.
The visit comes weeks after Chinese President Xi Jinping held a phone call with his Ukrainian counterpart Volodymyr Zelenskyy in late April, in the first talks between the two leaders since the war began.
On Twitter, Mr Zelenskyy described the call as "long and meaningful", while Mr Xi said China would focus on promoting peace. Although Beijing's proposals to end the conflict have been met with some scepticism in the West given its ties with Russia.
However, several European leaders, including French President Emmanuel Macron and European Commission chief Ursula von der Leyen, have urged Mr Xi to speak with Mr Zelenskyy and play a more active role in restraining Moscow's actions during a string of visits to the Chinese capital from March onwards.
Since February, Beijing has heavily promoted a 12-point proposal for a political settlement of the Ukraine crisis.
But the plan, launched on the first anniversary of Russia's invasion, was largely a reiteration of China's previous lines on the war. It urged both sides to agree to a gradual de-escalation and warned against the use of nuclear weapons.
Throughout the war, China has refrained from condemning its strategic ally Moscow or referring to its actions as an "invasion", leading to criticism from European countries and the United States, which have questioned China's credibility as a potential broker in the conflict.
Whatever message Mr Li delivers will be carefully scrutinised given the unease among Western nations over Mr Xi's meeting with his "dear friend" Russian President Vladimir Putin in March, and the two countries' commitment to a "no limits" partnership less than three weeks before the invasion, which Moscow called a "special military operation".
Reuters/ABC
