An argument over a regional lawmaker accused of anti-Semitism has laid bare divisions in the leadership of a German nationalist party that has been boosted by Europe's migrant crisis.

Thirteen out of 23 lawmakers left the caucus of Alternative for Germany, or AfD, in the southwestern state of Baden-Wuerttemberg on Tuesday after failing to get the rest to throw out legislator Wolfgang Gedeon. They included Joerg Meuthen, the party's national co-leader.

The other co-leader, Frauke Petry, later Tuesday said Gedeon had agreed to go and the split was averted.

However, deputy leader Alexander Gauland told ZDF television Wednesday that the split had gone ahead and criticized Petry for going behind other leaders' backs. He said the party had been damaged by Gedeon's behavior.