Leftist Russian opposition politician Sergei Udaltsov, freed this week after completing a four-and-a-half-year prison term, on Thursday urged a boycott of next year's presidential elections, calling them "dishonest."

"The authorities change electoral law like a swindler. They cut off candidates they don't like from the polls... there should be a consolidated boycott of the elections," Udaltsov said at a press conference in Moscow.

Udaltsov, 40, was a leading figure during the 2011-12 protests in Russia ahead of President Vladimir Putin's election to a historic third term.

He was convicted in July 2014 of fomenting mass riots in a case decried by rights groups and, including prison time before trial, served his term in full.

He was a leader of a banned radical leftist group which has since largely faded into obscurity, and said Thursday he is still in opposition to the government due to its "neo-liberal" economic policy.

"There has been no positive change all these years," he said, noting that although he is not planning to participate in the polls he did not rule out that a "young new face from the opposition" could emerge to represent the left.

Udaltsov was incarcerated in a penal colony in central Russia's Tambov province and he went on hunger strike several times.

Putin is widely expected to run in the March presidential polls though he has made no formal announcement.

Alexei Navalny, an anti-corruption politician currently considered the strongest opposition candidate, has announced he will run, though observers doubt he would be permitted to participate.

Udaltsov however criticised Navalny, underscoring that the opposition in Russia lacks unity. "He is not my candidate," Udaltsov said.

Source: AFP