Munich - Bavaria's Christian Social Union (CSU) lost its decades-old absolute majority on Sunday as voters defected to smaller parties in a state election seen as a test of support ahead of national polls next year.

Television projections based on early returns showed a swing of nearly 18 per cent away from the sister party of Chancellor Angela Merkel's Christian Democrats (CDU).

The CSU polled 42.8 per cent of the vote in its worst showing in half-a-century. The centre-left Social Democrats (SPD), which governs in a grand coalition with Merkel in Berlin, polled 19 per cent, slightly less than in the last state election in 2003.

Among the smaller parties, the conservative Free Voters entered the state parliament in Munich for the first time with 10.2 per cent and the liberal Free Democrats (FPD) were back after an absence of 14 years with 8.4 per cent.

The environmentalist Greens won 9.2 per cent, but the pro-Labour Left Party was hovering just below the 5 per cent needed for parliamentary representation.

In the elections in 2003, the CSU polled 60.7 per cent of the vote in the strongly Catholic state, where some of Germany's leading companies have their headquarters, including Siemens and BMW.

CSU Secretary General Christine Haderthauer said the disastrous result was a black day for the party which had ruled unchallenged for more than 40 years and will now be forced to look for a coalition partner.

"We have clearly failed to achieve our goal," she said in reference to the party's stated intention of retaining its absolute majority in the Alpine state.

   The CSU's good showing in Bavaria in the 2004 general election helped elevate Merkel to power, but its popularity declined after longtime leader Edmund Stoiber was ousted last year in a party revolt.

   Losses by the state-owned bank BayernLB, the scrapping of a prestigious super-fast train link to Munich airport and a controversial smoking ban led to voter discontent with the new leadership duo of Prime Minister Guenther Beckstein and party chairman Erwin Huber.

Analysts said the CSU would be forced to take up coalition negotiations with the FPD or the Free Voters, a regional party which campaigned on a platform of more local power.

   Beckstain, 64, appeared optimistic when casting his vote in Nuremberg on Sunday morning.

"I'm confident that we will receive a clear mandate to govern from the voters," he said, adding that there was no "Plan B" if his party failed to win an absolute majority. (dpa)