New Delhi, March 15 (IANS) Four Indian Army soldiers were killed and three injured during night firing practice of mortars at the Pokhran range in Rajasthan, an officer said Monday.

'The accident took place due to a barrel burst at around 8.45 p.m. Sunday. Four infantry soldiers operating the 81mm mortar were killed. Three others were injured and admitted to the military hospital in Jodhpur,' the officer told IANS, requesting anonymity as he was not authorised to speak to the media on the subject.

'A code of inquiry was ordered today (Monday),' he added.

The Indian Army's field firing range at Pokhran is the biggest and one of the busiest in the country. It is spread over an area of 30-40 km. The effective range of am 81mm mortar is between three-four km.

Two years ago, three soldiers had died in a similar accident at the same firing range.

'Though the inquiry is yet to start, we suspect a defecct in the ammunition, which was manufactured and supplied by one of our ordnance factories,' the officer said.

Indian ordnance factories are the biggest suppliers of 81mm mortar, a lightweight weapon that can fire six to eight rounds per minute.