In a statement issued by the official Korean Central News Agency, North Korea said it would only be able to afford to stop exporting missile technology if Washington lifted its economic embargo.

"If the US really wants to prevent our missile export, it should lift the economic embargo as early as possible and make a compensation for the losses to be caused by discontinued missile export," the agency said.

The agency said the US, which is still officially at war with Pyongyang, seeks to prevent the country defending itself.

It said as long as the US continued to target missiles at North Korean territory, it found "no reason to refrain from developing and deploying missiles to counter them".

"The discontinuation of our missile development is a matter which can be discussed after a peace agreement is signed, and the US military threat completely removed."

First response

The statement was the first response to an accusation by US officials that North Korea exported nuclear and missile technology to other nations including Pakistan, which carried out its first nuclear test in May.

Experts suspect that North Korea has supplied weapons technology to Pakistan as well as Iran, Iraq and Syria.

A BBC correspondent says that threatening to make trouble has been a favourite tactic of North Korea in the past.

Five years ago, it test-fired a missile into the sea in a demonstration that showed its neighbour Japan would be within range of its weapons.

International talks aimed at bringing a permanent peace to the Korean peninsula ended in failure in March. But relations between North and South Korea had been improving in recent weeks, though our correspondent says the current statement may set things back.