Russian President Vladimir Putin said on television Friday that almost 700,000 Russians are fighting in Ukraine.

"In the zone of our special military operation there are almost 700,000," Putin said during a televised meeting with decorated participants from the offensive.

In December at his end-of-year press conference, Putin gave the figure of 617,000 taking part in combat operations. He said that of those, 244,000 had been mobilised.

The latest figure on troop numbers comes after Russia in May launched a major ground assault in Ukraine's northeastern Kharkiv region.

Moscow rarely talks about the losses it has sustained through the conflict, which it still calls a "special military operation".

It last gave an official figure in September 2022, when it said 5,937 soldiers had been killed in combat.

But several independent analyses and assessments by Western intelligence services put Russian deaths well into the tens of thousands.

Russia has a manpower advantage over Ukraine on the battlefield.

Ukrainian President Volodymyr Zelensky has acknowledged issues with staffing and "morale" within Ukraine's often outgunned and outnumbered ranks.

Kyiv has lowered the age at which men can be drafted and tightened punishments for those who avoid the call-up.

"We need to staff the reserves... A large number of (brigades) are empty," Zelensky told AFP in May.

Zelensky said in February that around 31,000 Ukrainian soldiers had been killed in the first two years of the conflict.