Rights activists yesterday renewed calls for an end to martial law imposed since Thailand's coup, accusing the military of overseeing a judicial "twilight zone” following their power grab.

Army chief General Prayut Chan-O-Cha introduced the draconian law two days before the May 22 coup which he led swept the elected government from power.

He cited the need to restore peace and order after months of protests.

Prayut is now also prime minister and is due to lead the first meeting of a military-stacked cabinet today.

Martial law bans political gatherings, allows the detention of dissidents for up to seven days without charge and permits trials in a military court.

In the days and weeks following the coup more than 570 people were ordered to report to authorities, according to a report submitted by the Thai lawyers for Human Rights to the interior ministry.

It said more than 260 people were arrested with 87 now facing legal action, 61 of them in military courts.

Martial law "is tantamount to a twilight zone of judicial process during which the officials have broad powers without checks and review", the report said, adding such powers may lead to "serious violations... of fundamental human rights".

The release of the study, "The Human rights Situation 100 Days After the Coup", was scheduled last week but authorities warned its authors to postpone publication.

The report expressed particular concern over trials in military courts and the use of a controversial royal defamation law to protect key members of the monarchy.