BERLIN (Reuters) - German Chancellor Angela Merkel's centre-right coalition has inched ahead of the main opposition parties for the first time in two years, a poll showed on Sunday - thanks to a surge in support for the maverick Pirate Party at the expense of the Social Democrats.
An Emnid poll for Bild am Sonntag newspaper put Merkel's conservatives on 36 percent and their pro-business coalition partner, the Free Democrats (FDP), unchanged at 4 percent.
That puts the alliance short of a majority but just above the combined support for the opposition Social Democrats (SPD), who slipped one point to 26 percent, and their preferred partners, the Greens, unchanged at 13 percent.
If the poll heralds a trend, it could improve Merkel's chances of returning to power with the FDP to continue running Europe's biggest economy after federal elections in September 2013.
"The reason was the strong performance of the Pirate Party," said Emnid in its analysis.
The Pirates, who campaign for Internet freedom, were up one point at 10 percent, their highest level since October in the Emnid poll, having drawn support away from the SPD.
The party, whose popularity has surged since it won seats in two recent regional assemblies, has a bearing on national politics as it alters the coalition arithmetic.
Other recent polls have shown the two traditional centre-right and centre-left camps as being neck and neck. Although Merkel's conservatives have a lead of up to 10 points over the SPD, the FDP's weakness has cut her coalition options.
This has led many analysts to predict a "Grand Coalition" of conservatives and Social Democrats under Merkel's chancellorship as a likely outcome of the national election.
Analysts say the Pirates may sustain their recent success up to the federal vote. But a dispute at the weekend over whether the party's leaders should be paid showed the party still has work to do to prove itself on the national stage. It has refused to take a stance on several major economic and foreign policy issues.
"We must prove our ability. It damages us if we come across as being clueless," Joachim Paul, the party's candidate in next month's closely watched election in North Rhine-Westphalia, Germany's most populous state, told Der Spiegel weekly.
The FPD, whose support has collapsed since the 2009 vote, has also descended into infighting, its candidate in May's election in the state of Schleswig Holstein at the weekend attacking the party's direction under leader Philipp Roesler.
If the FPD performs badly in the two regional votes, Roesler is widely expected to be forced out. A successor may adopt a more combative stance, limiting Merkel's room for manoeuvre in areas such as child benefits, a big area of disagreement, and euro zone policy. The FDP is more sceptical about bailouts than Merkel's conservatives.
(Reporting by Madeline Chambers; Editing by Tim Pearce)