Japanese Prime Minister Yukio Hatoyama said Tuesday efforts are under way to secure the release "at any cost" of a Japanese engineer kidnapped in Yemen by tribesmen.

"We want to resolve (this case) at any cost," Hatoyama said, adding that the government is in contact with the Yemeni government. He did not give further information as the case is sensitive in nature.

While describing the case as "unfortunate," Hatoyama said the government has not received any information that the Japanese man has been hurt.

Chief Cabinet Secretary Hirofumi Hirano told a news conference Tuesday that the Yemeni government is working for the release of the man, adding that Tokyo has not been supplied with information about the captive's identity or condition.

Hirano said he was first informed of the incident on Monday morning.

According to the Japanese Embassy in Yemen, the man has been working for a private sector company that received an order for an aid project being undertaken in Yemen by the Japan International Cooperation Agency.