MOSCOW, Aug. 8 (Xinhua) -- The age of retirement in Russia could rise after the country's election commission on Wednesday approved a proposal to hold a national referendum on the issue.

The Central Election Commission (CEC) adopted a resolution stating that the proposal to vote for or against raising the retirement age corresponds to the Russian Constitution.

The proposal was made by three groups of citizens from Moscow city, Moscow and Altai regions.

At least two million signatures in no less than 43 out of the 85 federal subjects are needed for the referendum to be held, said head of CEC, Ella Pamfilova

She said that the preparation for a referendum is a time-consuming process, and that in a best-case scenario the vote will be held in February or March 2019, or at least no earlier than in the end of 2018.

In July, the State Duma, the lower house of parliament, passed a pension reform bill in the first reading to raise the retirement age to from 60 to 65 for men by 2028, and from 55 to 63 for women by 2034.

The bill awaits two more readings in the State Duma, and has to be approved by the upper house before being signed into law by President Vladimir Putin.

Thousands of people took to the streets in various cities to protest against the legislation. Recent polls also showed that the reform received little public support.

On Friday, State Duma Speaker Vyacheslav Volodin said that the lawmakers will return early from summer holidays to hold "large scale" hearings on the pension reform bill on Aug. 21.

Members of the government, representatives of the legislative and executive authorities of the Russian regions and republics, civil society institutions and experts are also expected to attend the hearings.