TOKYO, May 8, 2008 (AFP) - Two Japanese women, who were released within hours of being kidnapped in Yemen, apologised Thursday for worrying people back home and said they felt no threat to their lives.

"I am sorry for worrying many people in Japan," Keiko Mishima, 41, told reporters in Yemen, according to footage aired by national network Japan Broadcasting Corporation (NHK).

"I'm just relieved," added Shizuko Endo, 44.

The two tourists, who appeared to be unhurt, were taken hostage by tribesmen Wednesday as they travelled by road to the ancient Marib Dam, a major visitor attraction, a local official told AFP in Yemen.

The official said the kidnappers had been demanding the release of a member of the tribe who had been detained over an April bombing that killed three policemen in Marib.

Mishima said they had not felt their lives were in danger.

"In the car, they kept telling us not to worry and that there's no problem. After we were taken out of the vehicle, they gestured that we will not be harmed and things were okay," she said.

"So I didn't feel that our lives were threatened," she said.

The Japanese government thanked Yemen for its quick action in securing the release of the women.

"We are truly grateful to the Yemeni government which helped in an early resolution," Vice Foreign Minister Itsunori Onodera told reporters.

Onodera noted that Japan had earlier recommended that its tourists not to go to Yemen.

"The foreign ministry strongly wants (Japanese tourists) to refrain from going to this region," he said.

Mishima's mother, Sakae, said she was relieved to hear her daughter was safe.

"I'm able to breathe again after hearing they were freed. As I haven't talked to my daughter, however, I can't be fully relieved," the 62-year-old mother told the Jiji Press news agency.

The mother said her daughter frequently went abroad on holidays.

"Normally I only ask her where she's going. I never dreamed she would get into trouble," she said.

Foreigners are frequently seized by Yemen's powerful tribes for use as bargaining chips in disputes with the central government. More than 200 have been abducted over the past 15 years.