About 10 warships including a 3,000-tonne destroyer and three patrol boats took part in the one-day drill, Yonhap news agency quoted military officials as saying. The drill was held off the west coast town of Taean, far south of the disputed Yellow Sea border where the Cheonan corvette sank on March 26.

The exercise involved the testing of anti-submarine depth charges and naval guns, the military officials said.

Tensions have risen sharply since a multinational investigation concluded last week that a DPRK submarine fired a heavy torpedo to sink the Cheonan with the loss of 46 crew members.

On Monday the South announced a series of military, diplomatic and economic measures including a trade cut-off to punish the North. Among the military measures, Seoul will resume cross-border loudspeaker propaganda broadcasts which were halted six years ago.

Meanwhile, the DPRK has threatened to close the last road link with the South if Seoul goes ahead with propaganda broadcasts across the militarized border, as Washington pressured China to help persuade the DPRK to change its ways.

AFP- Reuters