Critics of a Russian pension reform bill have vowed to fight on until it reaches Vladimir Putin’s desk for signature, after the bill was passed by parliament.

The changes will raise the pension age by five years for men and women. The government has said the move is required to better balance the budget.

A poll published by the independent Levada Centre this week found that 86% of Russians had a negative view of the measures, and nearly a third said they were willing to protest.

Activists on both the left and right said they would continue to protest against the bill. On Wednesday the Duma, the lower house of parliament, accepted hundreds of amendments to the bill meant to assuage public anger.

“The Duma accepted the laws too hastily,” Yuri Vysokov, the press secretary for Essence of Time, a leftist movement, told the Guardian. He compared the passing of the bill to a “fever” that he said could “destabilise Russia and the world”.

“Soon this law will lie on the president’s desk. The question is whether he will give in to this strange fever or whether he’ll introduce a solution to the problem of the pension system in a constructive, democratic path,” Vysokov said.

Russia’s Communist party organised protests in cities across Russia this month, and its candidates have been the main beneficiaries of protest votes in recent local elections.

The opposition leader Alexei Navalny has also organised large protests against the measures.

The bill is expected to be reviewed next week by Russia’s upper house of parliament, the Federation Council, before going to Putin for his signature.