TOKYO: Japan grieved Tuesday over its greatest loss of life at militant hands since 9/11 as the carnage in Algeria provoked soul-searching for a people who have been relatively immune to Islamist terror.

There was blanket media coverage of the news that at least seven Japanese nationals had been killed in the Algerian hostage crisis, with the respected business daily Nikkei describing Japan's anger as "overwhelming".

Three other Japanese remained unaccounted for, after heavily armed Islamist gunmen overran the desert gas complex for four days before most were killed by Algerian security forces. At least 37 foreign hostages died in all.

A government plane was to leave Japan late Tuesday bound for Algeria. It was expected to return on Thursday with survivors and the bodies of those killed, all of whom were employees or contractors for Japanese engineering firm JGC.

"We lost many capable employees. I cannot find the right words," JGC spokesman Takeshi Endo said as he choked back sobs. "It's just unbearable."

The personal stories of the victims have stoked the sense of outrage in Japan.

It emerged that one of those killed was a 66-year-old engineer for JGC who was reaching the end of a long career in the world's trouble spots -- and had been sent back to Algeria at the last minute.

Several newspapers demanded that Tokyo beef up its intelligence operations and coordinate its responses to hostage crises with countries more versed in Islamist attacks, such as Britain and the United States.

The Nikkei said the Japanese government should also step up its efforts to safeguard nationals working in places that are increasingly important to the country's energy-starved economy.

"There is only so much Japan can do to collect information in the African continent. We should consider a structure under which relevant countries can effectively share information," it said.

"But at the same time, we must also arrange ways and methods to rescue Japanese nationals in case of emergencies."

The Mainichi newspaper echoed the call to boost intelligence and military cooperation with Japan's allies.

"The Japanese government's measures to deal with the situation were late because information necessary for crisis management did not come as it wished," it said.

Japanese people have been occasional victims of outrages around the world, but without any significant military involvement in wars in the Muslim world, the country has been largely sheltered from reprisal attacks.

The toll from the terror in Algeria is the highest for Japan since jihadists flew passenger planes into New York's Twin Towers, killing more than 2,700 people, including 24 Japanese.

The Mainichi warned that young Japanese eyeing a career abroad, doing jobs that could be vital to the country's prosperity, may be frightened off by the hostage crisis.

A 24-year-old postgraduate student at top-ranking Keio University in Tokyo told the paper he had been looking for opportunities in the region.

"I had believed that people in the Middle East are friendly toward the Japanese and I thought the Japanese are safer there than Westerners are," he said. "But this has made me worry."

Rokuro Fuchida, 66, was one of those Japanese who did forge much of their working lives overseas.

The JGC engineer believed his work in Algeria was done last year when he returned to Japan to celebrate New Year with friends and family, a relative told the Asahi Shimbun newspaper.

He was called back to Algeria to fix a glitch on a project just days before the militants began their rampage on Wednesday.

Ahead of his deployment, Fuchida wrote excitedly about his upcoming mission on his Facebook page.

"Next, I expect to be in Algeria on the African continent to see the starry sky!"

But as the relative put it to the Asahi: "Had he not returned, this wouldn't have happened."