A top adviser of JGC Corp. was among the seven dead and three missing Japanese employees of the Yokohama-based engineering firm caught up in last week's hostage crisis at a gas plant in southeast Algeria, JGC sources said Wednesday.

Tadanori Aratani, 66, a former vice president serving as one of two top advisers at the company, went to the gas plant in Ain Amenas several days before it was attacked by Islamist militants, according to the sources.

Neither the Japanese government nor JGC has revealed what happened to him.

Aratani was in charge of resources development projects, the sources said. Hailing from Tokyo, he entered the company in 1971 and served as vice president for about three years from 2009 before becoming a top adviser.

Takeshi Endo, chief of JGC's public and investor relations department, said Wednesday at a press conference in Yokohama that the search for the three missing Japanese continues. He reiterated that JGC policy requires that the seven Japanese killed in the ordeal not be identified, in order to not add to the stress and pressure on the next of kin. The government, at JGC's request, has also refrained from disclosing their names.

"The information from Algeria is limited. . . . Every possibility will be looked at" in the search, he said.

A government aircraft is expected to return with the bodies of the seven Japanese confirmed killed and seven others who survived the crisis. Algerian forces late last week apparently tried to end the hostage crisis by storming the gas complex, and scores were later reported killed, including hostages of various nationalities and their captors.