Japanese police have arrested four non-nationals in a widening probe into suspected al Qaeda activities in the country.
The government's top spokesman said he hoped the police action would yield clues about the activities of Lionel Dumont, a French national of Algerian descent who was arrested in Germany last December and had spent over a year in Japan until September.
"We have information that an al Qaeda-linked individual...had contacts with various people in the country and was engaged in certain activities. I hope that the details will be revealed," Chief Cabinet Secretary Hiroyuki Hosoda told a news conference.
Police searched 10 locations today following reports last week that Dumont, who has been linked to the al Qaeda network, had lived in Japan for several months after entering the country on a false passport in 2002.
"What is important for our nation's security is that we prevent an international terrorist organisation from operating," Hosoda said.
Dumont was believed to have been involved in delivering equipment and funds to al Qaeda during his stay in Japan, media reports have said.
Wednesday's investigation involved individuals with connections to Dumont, including a Bangladeshi man who police suspect has links to an Islamic group in Pakistan seeking independence for the Kashmir region, Japanese media said.
Police said they had arrested an Indian, a Malian and two Bangladeshis for violating immigration laws.
Referring to the Indian, a police official said: "We are aware of reports about his links to the French person and will try to find more about it through our investigation."
Television footage showed police officials at various buildings, including what were described as the homes of foreign Muslims and the office of a used car sales firm run by one of them.
Dumont, 33, had lived in Niigata, northwest of Tokyo, with his German wife from July 2002 until September 2003 and travelled frequently between Japan, Malaysia and Germany, media said.
Japanese police suspect that Dumont was trying to build up a base in Japan to support al Qaeda among a network of foreigners, Kyodo news agency said, adding that the police wanted to investigate their activities and cash transfers among them.
Dumont deposited and withdrew sums of several hundred thousand yen (€738) on about 45 occasions in a one-month period after he entered Japan in 2002, media reports have said.
Working with Pakistani colleagues, Dumont sold used cars to Russia and North Korea during his stay in Niigata, the Asahi Shimbun newspaper said.
Dumont had been wanted by Interpol in connection with various incidents including an attempted bomb attack against the Group of Seven summit in Lyon, France, in June 1996. He was sentenced to life imprisonment by a French court in 2001 in his absence.
Since the September 11, 2001 attacks on the United States, Japan has stepped up security at government offices and other key facilities and it has been on heightened alert since a letter purportedly from al Qaeda mentioned Japan as a possible target earlier this year.
Japan, a close ally of the United States, has sent some 550 ground troops to southern Iraqi on a non-combat mission to help rebuild Iraq.