Fearsome Chechen fighters have been airlifted out of the war zone after losing several hundred troops, Ukrainian military intelligence claims.
The Security Service of Ukraine (SBU) said the troops, also known as Kadyrovites, had returned to Grozny, the capital of Chechnya.
The organisation claimed that the soldiers had been pulled out after suffering large numbers of deaths in the first three weeks of the war.
Reports of Chechen troops participating in Russia's invasion of Ukraine began in the first days of the Russian invasion on February 24.
On February 26 a video began circulating of Chechen servicemen hoisting a Russian flag on a military unit building in Gostomel, a village 50 kilometres northwest of the Ukrainian capital.
The Armed Forces of Ukraine authenticated the video, but denied the claims within it that they had fought off three Ukrainian advances - saying that the area invaded was empty at the time.
A day later, three days after the invasion began, commander of the 141st Motorized Regiment of the Chechen Rosguard, General Magomed Tushayev, died.
During efforts to land at Gostomel airport from February 26 and 28, "several hundred" Chechen fighters lost their lives, SBU intelligence officers say.
A large column of what appeared to be Kadyrovites fighters and military machines was then filmed in Bucha, north of Kyiv.
Subsequent video emerged of airstrikes being launched at it and the wreckage of many of the army vehicles.
Ramzan Kadyrov, President of Chechnya, initially denied casualties among his fighters, but on February 28 he acknowledged the deaths of two Chechen servicemen, while not giving their names.
"Unfortunately, there are casualties among the natives of the Chechen Republic. Two died and six others were injured," he wrote on Telegram.
Claims from both sides regarding lives lost and the current location of troops are difficult to verify, given the contested area in which the Chechens were operating.
According to SBU counterintelligence, on March 13, the Kadyrovites were evacuated from the territory of the Kyiv region via Belarus and further by air to Chechnya.
At the same time, Kadyrov announced that he was sending a thousand more of his fighters to Ukraine.
Footage that has emerged in the last few days suggests that there are at least some Chechen fighters still involved in the invasion.
On Tuesday, Kadyrov announced that his fighters were leading the attack on the city of Mariupol, having entered Ukraine from the east.
He published a video which showed a number of soldiers firing at the upper floors of a building that had been hit by an airstrike, before they are seen appearing to help people evacuate.
Ukrainian troops have taken to taunting the Chechens, who come from a predominantly Muslim part of Russia.
Ukraine’s National Guard posted a video of fighters from the Azov Battalion, some members of which were accused of committing potential war crimes by the United Nations in 2016, greasing bullets in pork fat and warning them to go home.
