By Andreas Rinke and Paul Carrel
BERLIN (Reuters) - The European Union and the United States should consider banning from their ports Russian ships originating from the Sea of Azov after Russia captured three Ukrainian vessels there, German Chancellor Angela Merkel's protege said on Friday.
Annegret Kramp-Karrenbauer, who is leading the race to succeed Merkel as leader of her ruling conservatives, also said Germany must be ready to take more responsibility in foreign policy and to spend more on defense.
Russia seized the Ukrainian vessels and their crews on Sunday near Crimea, the Ukrainian region which Moscow annexed in 2014, over what it said was their illegal entry into Russian waters, which Ukraine denies.
"If it's confirmed that the aggression came from Russia ... then I think there must be a clear answer," Kramp-Karrenbauer told Reuters in a television interview.
"One answer might be, for example, to stop Russian ships coming from the region - from the Sea of Azov - from entering European or U.S. ports until this situation with Ukraine is resolved," she said.
The comments from Kramp-Karrenbauer, 56, mark a tougher tone than the posture adopted by Merkel, who has called for de-escalation and dialogue.
Kramp-Karrenbauer, sometimes referred to as AKK or "mini Merkel", is locked in a close race for the leadership of Germany's Christian Democratic Union (CDU) with Friedrich Merz, a long-time Merkel rival who promises more radical change.
Polls show she is more popular with CDU members and voters at large. The winner, to be decided in a vote by 1,001 delegates at a party congress on Dec. 7-8, will take pole position in the race to succeed Merkel as chancellor.
On foreign and defense policy, Kramp-Karrenbauer said Germany must be ready to do more -- a message sure to please U.S. President Donald Trump who has repeatedly pressed the German government to raise its defense spending.
"Europe - and in particular Germany - must assume more responsibility," Kramp-Karrenbauer said.
"We must be ready to take on this responsibility and that has consequences domestically. That means, for example, we must be ready to spend more money on defense at home and abroad."
Turning to trade tensions with the United States, Kramp-Karrenbauer said she was concerned about plans by top executives from German carmakers Volkswagen , BMW and Daimler to meet U.S. officials at the White House next week.
Trump has been threatening for months to impose tariffs on all EU-assembled vehicles, a move that could upend the industry's business model for selling cars in the United States.
"In the past, it has only been possible to avert punitive tariffs when we maintained a clear and strong position, for instance as the European Union," Kramp-Karrenbauer said.
"Given that, one must take care not to undermine such a strong, united political position through bilateral discussions."
The United States currently imposes import tariffs on cars assembled in the EU of 2.5 percent, compared with 10 percent tariffs for U.S.-built cars entering the European market.
(Additional reporting by Andrea Shalal; Editing by Gareth Jones)