By John Irish

PARIS (Reuters) - French President Nicolas Sarkozy said on Thursday he would follow the United States in starting a gradual troop withdrawal from Afghanistan, a move that could boost his popularity before a 2012 election.

Sarkozy said troops sent for reinforcement would start returning in a time frame similar to the U.S. force withdrawal. President Barack Obama said on Wednesday the United States would pull out 33,000 troops by late 2012.

"Given the progress we have seen (in Afghanistan), France will begin a gradual withdrawal of reinforcement troops sent to Afghanistan, in a proportional manner and in a calendar comparable to the withdrawal of American reinforcements," Sarkozy's office said after he spoke to Obama by telephone.

France has about 4,000 troops in Afghanistan, and has seen 62 soldiers killed. It is due to start redeploying and handing over areas it controls to the Afghan military in 2011.

The office statement did not say how many troops would be moved initially, and Defense Minister Gerard Longuet said details of the withdrawal would be kept quiet to avoid giving information to Afghanistan's Taliban insurgents.

"It will be significant for 2011 and, like the Americans, we will see this materialize in 2012," he told France Info radio.

French troops have been involved in the U.S.- and NATO-led Afghanistan operation since 2001 and there is growing frustration in political circles with the long campaign.

Nearly 10 years after a Taliban government was toppled, foreign forces have been unable to deal a decisive blow to the resurgent Islamist militant group. The Afghan government remains weak and notoriously corrupt, and billions of dollars of foreign aid have yielded meager results.

TIMING RIGHT FOR ELECTION

Obama said he would withdraw 10,000 of his 100,000 troops from Afghanistan by the year's end, followed by another 23,000 by the end of the next U.S. summer and a steady pullout of remaining troops after that.

French military analyst Jean-Dominique Merchet said Sarkozy's announcement suggested France could see 400 soldiers brought home by the end of the year and 1,300 by late 2012.

Sarkozy is expected to say in the last few weeks of 2011 that he will run for a second term in the April 2012 election.

His troops decision could be a boost to his chances in what looks set to be a tough battle for reelection against a resurgent left, with the far right also eating into his support.

The conservative has been edging back up in opinion polls since his erstwhile rival for 2012, Dominique Straus-Kahn, was knocked out of the race by a sex assault scandal, but he remains one of the least popular French presidents for decades.

"Sarkozy could present himself while announcing a withdrawal from Afghanistan. The Socialist opposition would be hard placed to criticize him on that as it has pushed for a coordinated withdrawal with the United States," Merchet wrote in a blog.

French Foreign Minister Alain Juppe has described the Afghanistan mission as a "trap" and in May said Paris was considering bringing forward the calendar to withdraw troops from the official 2014 NATO deadline.

(Editing by Catherine Bremer and Richard Meares)