Nine trekkers have died in a massive forest fire on the Kurangani Hills here in Tamil Nadu, an official said on Monday. Chief Minister K. Palaniswami ordered a probe into the incident.

A total of 27 trekkers were rescued from the blaze in Theni, some 520 km from here.

"Of the 27 rescued, 10 persons did not suffer any injuries and others suffered burn injuries," Theni District Collector Pallavi Baldev told reporters.

Health Secretary J. Radhakrishnan said of the 17 rescued, eight admitted to a Madurai hospital have suffered serious burn injuries.

The remaining are warded in the Government Hospital in Theni and in a private hospital at the request of the injured.

Indian Air Force (IAF) helicopters brought the remains of eight of the killed from the hills. The remains of one more person was earlier brought down by road.

The bodies have been sent for identification and they would be handed over to the relatives after autopsy.

Speaking to reporters, Palaniswami said the trekking expedition had been done without getting the necessary permission from the Forest Department.

He said a detailed probe will be held into the accident.

The IAF had mounted a search and rescue operation since Sunday. Apart from its 15 commandos, the IAF pressed three of its helicopters in the rescue mission.

The commandos flew from the Sulur Air Base near Coimbatore late on Sunday and climbed the hills.

What had started as an adventure trip for the trekking group of eight men, 25 women and three children turned into a nightmare on Sunday afternoon as they were caught up in the massive blaze.

The group had camped at a place up in the hills on Saturday night. They were supposed to return on Sunday.

Speaking to the media on Sunday, Baldev had said more than 20 trekkers were from the Chennai Trekking Club (CTC) and the others from Erode and Tiruppur.

The adventure was part of the Woman's Day activity that was celebrated on Thursday. The trekking expedition was organised by the CTC, an online group of over 40,000 members.

The CTC website does not have any name or number of the persons who are in-charge of the trekking expeditions.

According to the website, the CTC is a non-profit, volunteer group which organises outdoor sports, environmental conservation and social activities throughout the year on weekends and weekday mornings.

"Founded in 2008 the group has grown to one of the most active and largest in South India with over 40,000 members and hundreds of activities throughout the year.

"All activities are free -- expenses are shared equally among participants," says the website www.chennaitrekkers.org

An official of Tamil Nadu Fire and Rescue Services department told IANS that the terrain was tough and the approach to the accident spot was not motorable.

DMK leader M.K. Stalin expressed grief over the death of the trekkers.