Russian pop superstar Alla Pugacheva on Sunday denounced the Ukraine conflict and the "death of our boys for illusory goals" amid severe repression of any anti-Kremlin criticism.

This is the first time that the legendary crooner has publicly spoken out about the Ukraine offensive.

Her husband Maxim Galkin had just been recognised as a foreign agent – a label reminiscent of "enemy of the people" that has been used extensively against opponents, journalists and human rights activists.

"I am asking you to include me on the foreign agents list of my beloved country," 73-year-old Pugacheva told the Russian justice ministry – and her 3.5 million followers – on Instagram.

"Because I stand in solidarity with my husband, who is an honest and ethical person, a true and incorruptible Russian patriot, who only wishes for prosperity, peace and freedom of expression in his Motherland," Pugacheva said.

Pugacheva added that her husband wanted "the end of the deaths of our boys for illusory goals that make our country a pariah and weigh heavily on the lives of its citizens".

She became hugely popular in Soviet times and has remained so ever since.

The pop star's husband Maxim Galkin – a TV presenter now living abroad – has often criticised the operation in Ukraine.

Russian media said Pugacheva left the country after the beginning of the offensive.

She was seen in Moscow at the funeral of the last Soviet leader Mikhail Gorbachev – who tried to initiate democratic reforms – on September 3.

Russian authorities have clamped down on any criticism of the offensive in Ukraine, handing out fines and prison sentences.

Many Russian artists who denounced the conflict have had their shows cancelled.

Pugacheva has met several times with Russian President Vladimir Putin, but she has never publicly supported him. (AFP)