Berlin/Istanbul - Turkey has condemned a search operation by German marines that took place on a cargo ship in the Mediterranean as part of a wider EU mission to enforce the Libya arms embargo.

Turkey is not pleased with a German search operation

"We protest this action, which was conducted without authority and with the use of force," the Foreign Ministry in Ankara said.

German marines boarded the cargo ship some 20 kilometres north of Benghazi on Sunday to check its cargo, but then aborted the mission after Turkey, as the flag state, vetoed the search.

The Turkish Foreign Ministry described the action as "hypocritical and unlawful treatment" of Turkish cargo ships bound for Libya and said it "is not acceptable under any circumstances."

The ministry said the captain of the Rosaline A had been cooperative and provided information about the cargo, which is reported to have been carrying a consignment of paint.

"The entire personnel, including the captain, were subjected to a forced body search," it said, adding compensation would be claimed.

The German Defence Ministry said that "no forbidden goods were detected on board the carrier" up until the point the check was called off.

German opposition parliamentarians were sharply critical of the Turkish action.

Marie-Agnes Strack-Zimmermann of the liberal FDP called on German Foreign Minister Heiko Maas to take a stand.

It was unacceptable that Turkey repeatedly attempted to block checks on its vessels, she said.

For the hard left Die Linke, Sevim Dagdelen demanded that Germany halt all arms exports to its NATO ally Turkey.

The EU's Irini mission

Germany has since August been part of the European Union's Irini mission, which seeks to stop shipments of weapons to conflict-ridden Libya, as well as to tackle the smuggling of oil and fuel.

German marines abseiled down onto the vessel from a helicopter after no objection was voiced to the search by Turkey within four hours, a Defence Ministry spokesman said on Monday in Berlin.

He stressed that the decision to search the vessel had not been taken on board Germany's Hamburg frigate, but by the Irini mission command in Rome.

Since there had been no objection at first, "everything had gone smoothly in terms of procedure," said a Foreign Office spokeswoman.

Libya has been in turmoil since long-time ruler Moamer Gaddafi was toppled in 2011. The country became a proxy battleground for rival forces, and foreign powers have been drawn into the conflict.

Turkey is the main backer of Libya's UN-backed Government of National Accord (GNA) in Tripoli, led by Prime Minister Fayez Serraj, and has sent military personnel and equipment to back it up.

Serraj's rival, military strongman Khalifa Haftar, is backed by Russia, Egypt, Jordan and the United Arab Emirates, with reports suggesting he also receives military support.

The warring parties in Libya this month began UN-brokered direct political talks in a bid to find a time frame for national elections.

German government spokesman Steffen Seibert said on Monday that Germany, Britain, Italy and France supported this dialogue and welcomed efforts to draw up a road map for elections in December 2021. This is an important step towards "re-establishing Libya's sovereignty," he told reporters.