A centre-right regional government comprising the same parties as German Chancellor Angela Merkel's federal coalition has been ousted in Germany's northernmost state of Schleswig-Holstein.

Official results show no clear winner among the six parties which gained seats in the assembly in the regional capital of Kiel, leaving open the question of which governing coalition will emerge.

A new entrant in Kiel is the upstart Pirate Party. After campaigning for unrestricted internet access, it won 8.2 percent to secured seats in a third German regional legislature after entering the Berlin Senate last September and another regional state, Saarland, in March.

Despite having few detailed economic or foreign policies, the Pirates' surge deprives both the centre-right and centre-left blocs the outright victories they had sought. Many observers attribute the Pirate Party's gains to dissatisfaction among the German electorate with the country's political establishment.

Although Merkel's Christian Democrats (CDU) lost less than 1 of the vote in Schlieswig-Holstein, it was the worst result for the party in that state in five decades. They dropped from 31.5 percent in the last election in 2009 to 30.9 percent.

It was their coalition partners, however, who suffered the worst setback. The pro-business Free Democrats (FDP) slid from 14.9 percent to 8.2 percent. Nevertheless the party leaders were triumphant after surveys had initially predicted that they would not even clear the 5 percent threshold needed to win seats.

The communist Left Party also missed the threshold, attracting only 2.2 percent of the vote.

Centre-left gains

Making gains in Sunday's election, the opposition Social Democrats (SDP) increased their share of the vote by about 5 percent, securing 30.4 percent, while the Greens stood at about 13 percent.

Combined, this falls short of an outright majority, but the centre-left parties could be poised to form a coalition government with the region's Danish-speaking SSW party, which secured 4.6 percent and will again have seats in the legislature under a special provision.

Before polling, SSW leader Anke Spoorendonk said she would be in favor of joining the SDP and the Greens, saying she thought "a change of government will work."

According to a poll conducted by German public broadcaster ZDF, that coalition would have a narrow majority of 35 seats in the 69-seat Kiel legislature. But the Social Democrats' state leader Torsten Albig commented: "A one-seat majority is a one-seat majority."

Key test for Merkel

The ballot in Schleswig-Holstein has been seen as the first of two crucial tests this month for the German Chancellor.

Elections are due on May 13 in Germany's most populous state, North-Rhine Westphalia where recent polls suggest that her CDU party could again be in line to lose. Since 2010, NRW has been governed a coalition of Social Democrats and Greens. Losses are also predicted next weekend for the Free Democrats.

ccp/ipoj (dpa, AP, dapd)