Russian Prime Minister Dmitry Medvedev on Thursday proposed raising the pension age to 65 for men and 63 for women, the first hike for the country in almost nine decades.

A legacy of the USSR, Russia's retirement age -- set at 55 for women and 60 for men since the early 1930s -- is currently among the lowest in the world.

"We propose a relatively long transition period -- beginning in 2019 we propose incremental increases to reach retirement for men at 65 by 2028 and 63 for women in 2034," Medvedev said of plans which must now be approved by parliament.

"This will allow us to direct additional funds into increasing pensions above the rate of inflation," he added.

Given the country's demographic decline, the current system represents a growing weight for the federal budget.

President Vladimir Putin has repeatedly said that reforms would be necessary at some stage.

The Kremlin announced in March it would prepare measures to allow pensions to increase faster than inflation, as pensioners have particularly suffered from a surge in prices in recent years.

But the raising of the retirement age is expected to be a hugely unpopular move.

A petition against the measures created by Russian trade union groups on the website had already gathered more than 180,000 signatures ahead of Medvedev's statement.

"Forty percent of Russian men and 20 percent of Russian women do not reach the age of 65. In other words, if the retirement age is raised these people will simply not survive to have their pensions," representatives of the unions said in a statement.