Twenty people were on Friday detained under the National Security Act even as agitators stepped up civil disobedience movement for the removal of the Armed Forces (Special Powers) Act, 1958, from Manipur, official sources said.

District Magistrates of Imphal East and West districts issued the relevant orders declaring the 20 as detainees under NSA, the sources said.

Among those detained were the president of Zeliangrong United Club, Manipur, Maibon Phaomei and a local reporter, Ajit Singh.

At least 40 others who were also arrested in the past few days in connection with the ongoing agitation had been sent to judicial custody after being produced before the court of the chief judicial magistrate in Imphal on Thursday, the sources said.

Meanwhile, official reports said markets, shops and business establishments at Khwairamband in Imphal remained closed on Friday.

Most of the public transport services also remained suspended, the reports said.

No untoward incident was, however, reported from any part of the state.

Most of the 40 people remanded to judicial custody were students and prominent members of the All Manipur Social Reformation and Development Samaj, a major women's organisation in Manipur, the sources said.

Meanwhile, the United Committee Manipur in a statement warned the state government of "dire consequences" if the authorities went ahead with arresting prominent social activists.

The statement said, "The people of Manipur have been demanding the removal of the Act, which empowers the security forces to kill innocent civilians and if the government attempts to suppress human rights, it will result only in chaos and disorder."

"We want to live just like other Indians and are not demanding anything more than this," the statement signed by UCM secretary general Khoirom Gourshya said.