North Korea warned Friday that US delays in resolving the nuclear dispute could slow down work to disable its atomic plants, state media reported.

The warning comes just as North Korea was reported to have fired several
short-range missiles off its west coast.

The reported missile launch comes amid rising tensions between the two Koreas.

The South Korean Yonhap news agency, quoting a government source, said the missiles were fired at 10.30 am (0130 GMT) into the Yellow Sea.

It said South Korean military authorities are closely watching the North's military movements.

Defence ministry officials said they were checking the report.

Yonhap gave no further details of Friday's launch, but said the communist state had prepared earlier this week for a missile launch that did not go ahead at the time.

It also said the North had banned ships from part of the sea between Tuesday and Wednesday morning while a 150-ton navy boat equipped with ship-to-ship missiles was on standby off the western port of Nampo.

On Thursday, the North expelled South Korean officials working at joint industrial complex north of the heavily armed border.

The move was said to be in retaliation for a hard-line stance taken towards Pyongyang by South Korea's new conservative government.