Fresh Russia protests under way against Putin victory.

BBC - Fresh protests are under way in Moscow and other Russian cities following Vladimir Putin's victory in last weekend's presidential election.

Several thousand people are lining one of central Moscow's main avenues, with correspondents saying turnout could be the key to future opposition strategy.

A wave of protests was sparked last December by evidence that parliamentary elections had been rigged.

Similar allegations have surrounded the presidential vote.

Foreign states have accepted Mr Putin's election for a third term but observers said the poll had been skewed in his favour.

The BBC's Richard Galpin in Moscow says some opposition leaders are playing down expectations of a huge turn-out on Saturday, partly because their movement has failed to stop Mr Putin securing another term.

The Moscow protest is taking place on Novy Arbat, a vast avenue lined by 1960s skyscrapers.

BBC correspondent says several thousand have so far gathered, with more arriving.

The city authorities have allowed a rally of up to 50,000 people.

On a cold but sunny Moscow day, demonstrators waved banners and wore white ribbons - the symbol of the protest movement.

Protest organiser Vladimir Ryzhkov told the crowd: "These authorities are illegitimate. The same people are in power, the same people who took away our right to choose, the same people who destroyed freedom of speech and political competition.

"We will continue to demand deep political reforms and new elections."

Dozens of police and military vehicles have been stationed on the streets near the avenue.

"If we achieve a growth in the protests, if 100,000 people come out, it means we can quickly get results," said Sergei Udaltsov, one of the protest organisers.

"If there won't be that number, it means that there will be longer-lasting work."

Last Monday, a day after the election, police arrested about 250 protesters in Moscow and another 300 in St Petersburg.

Moscow officials say about 2,500 troops, police and civilian auxiliaries will be on duty in the city on Saturday, Itar-Tass news agency reported.

Mr Putin was re-elected for six years, having served two previous terms as president between 2000 and 2008.

On Friday, US President Barack Obama called Mr Putin from Air Force One "to congratulate him on his recent victory", a White House statement said.

Mr Obama said he looked forward to hosting Mr Putin at the G8 Summit in May at Camp David.