French President Nicolas Sarkozy has lost ground to his Socialist rival in the past two weeks of campaigning, an opinion poll showed on Sunday, predicting front-runner Francois Hollande would easily win the May 6 presidential election runoff.

The poll for LH2-Yahoo showed Sarkozy losing 3 percentage points to 23 percent while Hollande slipped 1.5 percentage points but remained well ahead on 30.5 percent of voting intentions for the April 22 first round.

If the second round runoff were to be held today, Hollande would get 58 percent of votes and Sarkozy 42 percent.

Centrist candidate Francois Bayrou gained 2 percentage points to 15 percent, putting him in third place alongside National Front candidate Marine Le Pen, who gained 1 percentage point.

The poll suggested Sarkozy had lost some support among the retired and elderly and supporters of his conservative UMP party, saying it was a sign of Sarkozy's difficulty in generating a positive dynamic.

Several surveys have shown that the conservative leader, who is battling the worst poll ratings of any French leader seeking re-election, received a bounce immediately after launching his campaign officially in mid-February.

But he suffered setbacks last week. Hollande has proposed taxing those earning more than 1 million euros a year at a rate of 75 percent, an idea approved of by 61 percent of voters, according to a survey released on Friday.

Sarkozy, meanwhile, was forced to seek refuge in a bar protected by police after he was mobbed by left-wing militants and Basque separatists during a campaign visit to Bayonne near the Spanish border on Thursday.

Sarkozy marked a shift to the right in his campaign on Saturday to try to shore up support on the right of his party and entice voters away from the National Front by pledging to cut the number of immigrants, rejecting multi-culturalism and calling for clear labelling of halal meat.

Attitudes towards immigration and Europe's largest Muslim minority have long been an electoral issue in France. Sarkozy was accused of courting the far right when he won power in 2007.

Commenting on Sarkozy's proposals, Pierre Moscovici, Hollande's campaign manager, told RTL radio on Sunday: It stigmatizes in an underhand manner Muslims in France and echoes the proposals of the National Front. It's a mistake.

(Reporting By Daniel Flynn and Sophie Louet; Editing by Janet Lawrence)