Mikhail Gorbachev, the Soviet Union's last leader, has called on Russian authorities to annul the disputed results of parliamentary elections and hold a new poll as popular indignation grows over allegations of fraud.

Gorbachev told the Interfax news agency on Wednesday that authorities must hold a fresh election or deal with a rising tide of discontent following protests against the results of Sunday's election.

"More and more people are starting to believe that the election results are not fair," Gorbachev said. "I believe that ignoring public opinion discredits the authorities and destabilises the situation."

Thousands of Russians have rallied in the capital, Moscow, and in the city of St Petersburg in the last two days, facing off against tens of thousands of police and interior ministry troops. Hundreds of protesters have been detained in both cities.

Shaun Walker, The Independent's Russia correspondent, told Al Jazeera that up until now, "the Kremlin's response has been fairly inadequate".

"It was very easy to dismiss [the protesters] as marginal radicals when only a couple of hundred showed up," he said, adding that this needs to be thought out again the more the numbers of protesters increases.

"Any real attempt to engage with these people has not really been forthcoming," he said.

'Ballot stuffing'

Several thousand people first took to the streets of central Moscow late on Monday to protest against alleged fraud and voting irregularities after Prime Minister Vladimir Putin's United Russia retained power, albeit with a greatly reduced share of the vote.  

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Opposition parties and international observers said the vote was marred by vote-rigging, including alleged ballot-box stuffing and false voter rolls.

Gorbachev said on Wednesday that authorities "must admit that there have been numerous falsifications and ballot stuffing".

Sunday's parliamentary vote suggested Russians are tiring of Putin and his United Russia party, which has dominated all other political forces in Russia for the past dozen years and earned a reputation for corruption.

Putin, meanwhile, officially registered on Wednesday to run for the presidency in March, but the unusually sustained protests of the past two days suggested his drive to retake the job he held from 2000-2008 may not go as smoothly as he had expected.

Hundreds of people protested in Russia's two largest cities, Moscow and St Petersburg, on Wednesday.

Thousands of security forces were out in the Russian capital and helicopters roamed the sky, a show of force following two days of protest.

Another protest planned

Authorities said on Tuesday that at least 51,500 police officers and 2,000 interior ministry troops had been deployed in Moscow since the election. Unlike the police, interior ministry troops are an armed force, largely manned by conscripts.

The allegations of election fraud have fired up the opposition, which has long seen its protests crushed and its pleas ignored by the Kremlin-dominated media.

On Facebook, nearly 15,000 people signed up to a page announcing an opposition rally for Saturday - many of whom have never taken part in political protests.

Mariya Boyarintseva, a 24-year-old event manager, told The Associated Press news agency that she had never been to a political rally before but she was going to Saturday's protest.

Boyarintseva said she didn't go to rallies Monday or Tuesday in Moscow, which ended with clashes with police and hundreds detained, because "it felt a bit scary".

"Now, I have a feeling that I ought to go," she said.

Source: Al Jazeera and agencies