N Korea fires short-range missiles, South says 'provocative'

North Korea fired short-range missiles into the sea off its eastern coast for the second time in a week today, prompting a warning from South Korea of "reckless provocation".

The missile tests have clearly been timed to coincide with annual South Korea-US military exercises which kicked off a week ago and run until mid-April.

Two missiles were fired today and both flew around 500 kilometres into the Sea of Japan, according to South Korea's Defence Ministry.

Four short-range Scud missiles were fired in similar fashion on Thursday.

Both tests were condemned by Seoul, which urged the North to cease all testing immediately and said it would consider calling for sanctions.

"The North is taking a double-faced stance by making conciliatory gestures on one hand and pushing ahead with reckless provocation on the other," said Defence Ministry spokesman Kim Min-Seok.

The Scuds are at the longer edge of the short-range spectrum, with an estimated reach of 300-800 kilometres -- capable of striking any target in the South.

It is not unusual for North Korea to carry out such tests, which often go unreported by South Korea.

But Kim said the Scud firings were of particular concern.

"We believe that the North is testing various ballistic missiles with various ranges as a show of force to threaten us," he said.

Washington initially played down Thursday's firings, but later suggested they violated UN sanctions imposed on the North's missile programme.

UN Security Council resolutions prohibit North Korea "from launching any ballistic missile, and this includes any Scud missile", Pentagon spokesman Colonel Steven Warren said Friday.

Pyongyang routinely condemns the South-US joint exercises as rehearsals for invasion.