SEOUL, S KOREA - North Korea Friday fired a short-range missile off its east coast, the sixth since it staged a nuclear test earlier this week, South Korea's Yonhap news agency said.

The defence ministry declined comment but the news agency's reports of five missile launches earlier this week were later confirmed.

The latest missile was launched in the early evening Friday, Yonhap quoted an unidentified Seoul government official as saying.

All five missiles fired Monday and Tuesday were also launched off the east coast of the communist state, the defence ministry said Wednesday, describing them as a possible display of firepower.

They reportedly had a range of 130 kilometres (80 miles).

Several times in recent years, the North has test-fired short-range missiles in either the Yellow Sea or the Sea of Japan (East Sea). The exercises are often staged to coincide with periods of regional tension.

The North's jet fighters have more than doubled the number of missions near the land border amid the growing tensions, military officials have said.

Following the North's nuclear test on Monday, the second since October 2006, the South announced it has joined a US-led international initiative to halt the trade in weapons of mass destruction.

The North responded Wednesday by repudiating the armistice which has governed the peninsula for half a century and threatening attacks on the South.

On Friday Pyongyang vowed to take 'additional self-defence measures' if the UN Security Council imposes fresh sanctions for its nuclear test. --AFP