The United States has imposed sanctions on a Pakistani institute accused of purchasing Nodong missiles, which have a range of 800 miles, from North Korea, The Washington Post quoted officials as saying on Monday.

Last week, Secretary of State Colin Powell notified Pakistan President Pervez Musharraf of the sanctions against The AQ Khan Nuclear Research Institute.

The institute will not be able to do business with the US government or companies for two years.

The same rules apply to Changgwang Sinyong Corp, the North Korean entity that sold the missiles.

The sanctions also apply to the North Korean government, because it controls the firm.

However, the sanctions are largely symbolic, because neither the Pakistani institute nor North Korea does business with the US.

But it does send a strong message to North Korea, which the US is trying to isolate, and Pakistan, which is an ally of the Bush administration in the war against terror.

"We want to make clear to people that buying weapons from North Korea has a direct and negative impact on the security of the United States," The Washington Post quoted an official as saying.

A spokesman for Pakistan's embassy in Washington denied that the institute had acquired Nodongs.

"We beg to differ. Whatever missile technology we have is indigenous," the newspaper quoted him as saying.