Eleven security personnel and four Maoist rebels were killed in a 10-hour gunbattle after the rebels laid siege to India's largest bauxite mine in the eastern state of Orissa, police said Monday.

A group of 100 armed Maoist rebels laid siege to the state-run National Aluminium Company's bauxite mine at Panchpatmali in Koraput district, some 370 kilometres south-west of Orissa's capital Bhubaneshwar late Sunday.

At least 80 mine employees, who were about to leave the mine when the rebels attacked, were held hostage, Orissa police chief MM Prahraj was quoted as saying by Times Now television channel.

The Maoists fled after a 10-hour gunbattle that ended in the early hours of Monday and all mine employees were safe, Prahraj said.

The rebels also attacked a nearby camp of the Central Industrial Security Force (CISF) which looks after security at the mine.

"Eleven CISF personnel and four Maoists were killed," Prahraj said.

Some arms and ammunition were reportedly looted from the CISF armoury, Times Now reported.

The entire area was booby trapped with landmines, making it difficult for police and paramilitary support forces to reach the area.

Orissa's Koraput district is due to hold balloting on Thursday in the first phase of India's general elections.

Maoist rebels have upped their attacks on government installations in the run-up to the elections, reported dpa.