FOURTEEN Muslims, including Japanese nationals, have filed a lawsuit against the Tokyo and state governments, contending that anti-terrorism investigations by police violated their freedom of faith.

The 14 plaintiffs are demanding a total Y154 million ($1.81 million), or Y11 million each, in compensation for damage after details of what they called an "illegal terrorism investigation" against Muslims were leaked.

More than 100 documents, dated 2004 to 2010 and including data from the FBI, were leaked online in November giving details on people co-operating with terrorism inquiries and on foreigners under investigation in Japan.

The documents came from the Tokyo Metropolitan Police Department's Public Security Bureau and included details on Islamic terrorism suspects and on police informants.

But lawyers for the group - whose own information was leaked - yesterday said 98 per cent of Japan's 72,000 Muslims had been monitored.

For some of them, the private information included not only their names, photos, family members and addresses but also details of their actions such as visits to mosques and internet habits, the lawyers said.

"It has come clear that if you are a Muslim or have any sort of relations with them, you are immediately put under police surveillance," said lawyer Kazuyuki Azusawa.

One of the most serious violations of religious freedom was undercover officers tailing Muslims from mosques, he said.

A store owner in his 40s who didn't want to be identified said he saw his store sales halved after the details were posted.

"I cannot even go back to my country because I may be detained as a suspect of terrorism," he said. "I want the Japanese police to fix my life."

Muslims are a minority religious group in Japan, mostly foreigners, many of whom married Japanese and settled here. But there are some Japanese who have converted to Islam, and the 14 involved in the lawsuit include some converts.

Originally published as Muslims sue over Japan anti-terror probe