At least three Indian soldiers were killed when a gun barrel exploded during a military exercise between India and Singapore in the country's northern Uttar Pradesh state, police said Sunday, according to DPA. "The soldiers were killed during the exercises on Saturday when the barrel of the field gun they were testing, accidentally burst," senior police officer D S Chauhan said. There were no other injuries, he said. The week-long exercises were on at the 7 Artillery Guards unit located at the Babina Field Firing Range in Jhansi, some 340 kilometres south west of state capital Lucknow. India and Singapore have been conducting military exercises as part of a bilateral agreement to boost defence cooperation. The two countries are presently carrying out joint air exercises at the eastern Kalaikunda airbase which are scheduled to conclude by January 20.