Japan has confirmed that at least seven of its nationals died after they were taken hostage by militants in Algeria.
Japanese Prime Minister Shinzo Abe, late Monday in Tokyo, confirmed what had been feared in recent days - that most of the Japanese engineers unaccounted for at the besieged natural gas complex in the Algerian desert had been killed.
Abe says the bodies of seven Japanese engineers were located in an Algerian hospital.
The prime minister says their deaths are "extremely regrettable" and the act of terrorism at the Japanese-built facility is "despicable" and "unforgivable."
He adds that he is at a loss for words when thinking about the family members of those who were killed.
Abe says his government will continue working with the international community to fight terrorism.
Three more Japanese, who were employees of JGC Corporation, remain missing. Seven other Japanese managed to escape. The prime minister says he has instructed his staff to take all possible measures to locate those who are still unaccounted for.
Algeria's government says at least 37 foreign nationals died after Islamists stormed the natural gas refinery at In Amenas last Wednesday. Besides Japanese employees of the facility, American, British, French, Norwegian, Filipino and Romanian workers also died.
Japanese officials say they have unanswered questions about the response taken by Algeria's military. Its forces on Thursday opened fire, saying the kidnappers were attempting to escape with some of the foreign hostages.
Algeria says five of the attackers were captured alive Saturday.
Islamist Mokhtar Belmokhtar, in a video posted on the Internet, has claimed responsibility. He says he was acting in the name of al-Qaida and that the attack was conducted, in part, as a response to the French military operation against al-Qaida linked militants in Mali.