Three Dutch marines were captured by forces loyal to Moammar Gadhafi during a rescue attempt of two European workers and are being held by Libyan authorities for five days, a Defense Ministry spokesman said Thursday.

The two Europeans, one Dutch and one whose nationality was not released, were handed over unharmed to the Dutch embassy in Tripoli Thursday and have left Libya, the ministry said.

The three were surrounded by armed men on Sunday after landing near Sirte in a Lynx helicopter from the navy ship HMS Tromp, which was anchored off the Libyan coast to help evacuations from the conflict-torn country, spokesman Otte Beeksma told The Associated Press.

Dutch officials are in "intensive negotiations" with Gadhafi's government to secure the marines' release, he said.

"We have also been in contact with the crewmen involved," Beeksma said. "They are doing well under the circumstances and we hope they will be released as quickly as possible."

Defense Minister Hans Hillen welcomed the news that the two Europeans were safe and had left Libya. "Everything is being done to also get the crew safely out of the country as soon as possible," he said in a statement.

Asked if the Dutch government considered the marines hostages, Beeksma said, "they are being held by Libyan authorities."

Prime Minister Mark Rutte said news of the men's capture was kept quiet to assist talks on their release. Dutch daily De Telegraaf first reported their capture in its Thursday edition.

"These are situations that benefit from total secrecy because then you can carry out discussions in peace to ensure these people get home safely," he told national broadcaster NOS.

"It is terrible for the crew of the Lynx helicopter," Rutte said. "Everything is being done to make sure the crew gets home."

The identities of the marines were not released.

News of the marines' detention by Gadhafi came a day after anti-government rebels fought off forces loyal to Gadhafi in a fierce battle for Brega, a strategic oil facility 460 miles (740 kilometers) east of Gadhafi's stronghold in Tripoli.

Gadhafi's crackdown has been the harshest in the Arab world to the wave of anti-government protests sweeping across parts of the Middle East and North Africa. His forces are regrouping in an attempt to regain territories now controlled by opponents of his regime.

Later Thursday, the prosecutor of the International Criminal Court, Luis Moreno-Ocampo, is scheduled to announce he is opening an investigation into possible crimes against humanity committed in Libya.