The EU has joined the US in saying that Vladimir Putin's party probably did not win recent elections with anything like the 50 percent of votes it claims.

The EU diplomatic service in a statement on Tuesday (6 December) said: "Reports of procedural violations, such as lack of media impartiality, lack of separation between party and state and the harassments of independent monitoring attempts, are ... of serious concern."

With thousands of anti-Putin protesters planning to mass in central Moscow for a second night running despite a show of force by the army, EU spokeswoman Maja Kocjancic added: "The demonstrations we are seeing following the elections must be seen against the background of what we've said - the lack of independent media, the reports of procedural violations - generally speaking, and this is always our line, the right of people to freedom of assemby and freedom of expression should be respected."

US secretary of state Hilary Clinton at a press briefing in Bonn, Germany on Monday, was more blunt.

She said "election-day attempts to stuff ballot boxes [and] manipulate voter lists" were "totally contrary" to basic rights, adding: "Russian voters deserve a full investigation of all credible reports of electoral fraud."

Prime Minister Putin, who is preparing to rule Russia for another 12 years after he takes back the presidency in March, on Tuesday promised to reshuffle the government in response to his dip in popularity.

The official 50 percent result for his United Russia party is 14 percent less than in 2007 amid disconent over economic stagnation and corruption.

Brussels-based NGO Transparency International last week put Russia on par with Nigeria in its corruption report, while London-based think-tank the European Council on Foreign Relations (ECFR) reckons United Russia would have got just 30-35 percent of votes in a fair ballot.

A Russian diplomat told this website that Putin in his first term as president in 1999 had to restore order after the collapse of the Soviet Union. But in his second term, he will bring in liberal reforms, good governance and rule of law.

But opposition politicians do not buy the Kremlin line.

At a recent congress organised by the European Parliament's Liberal group in Helsinki, opposition leader and former Russian prime minister Mikhail Kasyanov predicted that popular unrest will grow. "The country is becoming a shambles and an Arab Spring situation is becoming inevitable," he said.

The ECFR in an op-ed published in EUobserver on Tuesday cast doubt on the Kasyanov scenario, however.

"The outcome of Sunday's elections should not be mistaken for imminent change. Authoritarian regimes can survive decades of unpopularity, especially if they are also among the world's largest oil and gas producers," it said, noting that Russia might be heading for "a nastier turn" in terms of repression.

For his part, Putin spokesman Dmitri Peskov on Tuesday - as army trucks rolled into the city centre - warned that the right to freedom of assembly "must be handled in an appropriate way concering participants in unauthorised demonstrations."