A married couple from Myanmar who have been in detention for illegally entering Japan filed a lawsuit Friday with the Tokyo District Court, seeking cancellation of the government's order to hold them and demanding their release.

The couple's lawyer said his clients had been living in Tokyo with their 1-year-old son and 3-year-old daughter when they were taken into custody by immigration authorities and separated from their children.

The couple said their detention is inhumane because they have been separated from their children, who have been placed in a facility for children.

According to the couple's petition, they belonged to an ethnic minority in Myanmar and took part in an antigovernment movement, and to escape persecution, they fled to Japan, entering the country on fake passports sometime before or in 1999.

The two married in Japan and took on jobs, including as janitors. Last month, law enforcement authorities took the husband into custody first, then the wife about two weeks later.

Since they have no relatives in Japan, the two children were placed in the facility, the lawyer said, adding that they had high fevers at the time.

The lawyer criticized the detention of the couple, saying they pose no flight risk because the family has created a life in Japan.