The launches, which came two days after North Korea fired four short-range cruise missiles, will likely further escalate tensions in the region as the US tries to muster support for tough enforcement of the latest UN Security Council resolution imposed on the communist regime for its May nuclear test.

South Korea's Joint Chiefs of Staff said three missiles were fired early today, a fourth around noon and three more in the afternoon.

The Defence Ministry said that the missiles were ballistic and are believed to have flown more than 250 miles (400 km).

"Our military is fully ready to counter any North Korean threats and provocations based on strong South Korea-US combined defense posture," the Joint Chiefs of Staff said in a statement.

South Korea's Yonhap news agency quoted military officials as saying the missiles appeared to be a type of Scud missile. North Korea's Scuds are considered short-range, the South's military said.

But Yonhap also said that it is possible they could have been longer-range Rodong missiles fired a shorter distance.