Martin Slotty, an official spokesman, said the Klarsfelds, along with at least three other protesters still being held in jail, would probably face charges of resisting arrest, harming police and freeing other protesters from police detention.
Others in the group, which comprised some 50 Jews from France and gypsies, were also being investigated and could be charged with disturbing the peace and possessing weapons, he said.
Jewish community leaders in Berlin expressed dismay at the news, particularly given the Rostock authorities' less than speedy response to the outbreak of attacks on foreigners in Germany which erupted in the city in August.
'In comparison to the brutal right-wing attacks on foreigners in the city, this protest was harmless,' said Jerzy Kanal, the leader of Berlin's Jewish community. 'It is a totally exaggerated reaction - and shows an alarming underlying attitude of the authorities.'
Serge Klarsfeld himself, now back in Paris, said that if he and his wife were called to stand trial in Rostock, they would choose a moment to return calculated to cause maximum embarrassment - perhaps when Chancellor Helmut Kohl and President Francois Mitterrand hold their next summit meeting.
Monday's protest in Rostock was aimed primarily at drawing attention to the recently concluded deal between Bonn and Bucharest under which gypsies turned down for asylum in Germany will be forcibly deported back to Romania.
After staging a noisy street protest, four members of the group entered the city hall and hung a plaque on one of its walls recalling the millions of Jews and gypsies murdered by the Nazis and drawing a parallel with the racist violence in Rostock. Scuffles broke out after police were called in to break up the protest; 46 Jews were arrested, most of them were detained for the night.
According to Mr Slotty, several police were wounded after some of the protesters aimed tear-gas at them in an attempt to prevent the arrest of some of their colleagues. Damage was also reported to cars and some onlookers complained of being roughly treated for refusing to accept leaflets from the group.
Of the 46 protesters arrested, 43 were released the next day. The continuing detention of the remaining three has been fiercely criticised by Jewish leaders.
'The city authorities were plainly angry with us because we were denouncing xenophobia in this part of Germany,' said Mr Klarsfeld. 'There was no justification for swooping on us and treating us like hardened criminals. It was a completely unreasonable response, and an attempt to disguise the real issue - the fact that Germany is once again about to start deporting gypsies.'Reuse content