Updated

A draft report released by a former U.N. weapons inspector found that the international smuggling ring that supplied nuclear designs to Iran, Libya, and North Korea also obtained the blueprints for an advanced nuclear warhead, The Washington Post reported Sunday.

David Albright, a well-known nuclear weapons expert, said that designs for a nuclear device small enough to fit on a ballistic missile were found on computers belonging to the now-defunct smuggling ring of rouge Pakistani nuclear scientist Abdul Qadeer Khan.

Khan — who remains under house arrest in Pakistan for selling nuclear technologies — supplied secret nuclear blueprints to Libya, North Korea and Iran, according the Post. The U.N. nuclear watchdog, the International Atomic Energy Agency, has been conducting an on-going investigation into what other secrets may have sold by A.Q. Khan.

Albright's report said what is troubling about these electronic blueprints — discovered in 2006 on the computer of a Swiss businessman — is that it shows the existence of another, more sophisticated design than the one sold to Libya — better suited the missile capabilities of countries such as Iran.

Swiss authorities, under the direction of the IAEA reportedly destroyed the computer contents, said the Post.

But Albright — who is known for exposing the location of Iran's secret nuclear facilities — warns the electronic blue-prints, made up of hundreds of pages of documents, could easily be copied and shared with a number of countries, according to the newspaper.

"These advanced nuclear weapons designs may have long ago been sold off to some of the most treacherous regimes in the world," Albright wrote in his report, which was obtained by the newspaper.

Albright’s report is expected to be published later this week.

Click here to read more on this story from the Washington Post.