Saarland, a state of coalmines and steel plants, was formerly SPD heartland. The gains were credited to Oskar Lafontaine, a former SPD state premier who defected to the Left Party in 2005 and is now its co-leader.

In industrialized Saxony, the CDU maintained its support (40.7 percent). The Left (20.9 per cent) overshadowed the SPD, which again won only 10 percent, level-pegging with the FDP.

CDU officials appealed to Merkel to perk up her general election campaign. So far the national campaign has been lacklustre, with no sharply delineated issues separating the SPD and CDU.

Merkel, whose national support is rated at 36 percent, said earlier she did not regard the state polls as a test.

The far-right National Democratic Party (NPD) again gained seats in the Saxony state assembly, winning 5.5 percent of the vote, but that was a sharp fall from the 12 percent it won five years ago.