The ring, led by Pakistani nuclear scientist Abdul Qadeer Khan, is previously known to have sold bomb-related parts to Libya, Iran and North Korea but is now believed to be defunct.
The drawings were discovered in 2006 on computers owned by Swiss businessmen.
They were recently destroyed by the Swiss government under the supervision of the UN nuclear watchdog, the International Atomic Energy Agency (IAEA), to keep them out of the wrong hands.
But UN officials said they could not rule out that the material had already been sold.
"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 the draft report, which was expected to be published this week, the Post said.
|Abdul Qadeer Khan is still seen as a national |
hero by some in Pakistan [EPA]
In Vienna, a senior diplomat speaking on condition of anonymity said the IAEA had knowledge of the existence of a sophisticated nuclear weapons design being peddled electronically by the black-market ring as far back as 2005.
Khan, the architect of Pakistan's nuclear programme, has been under house arrest in Islamabad since 2004 after admitting he sold nuclear secrets to North Korea, Libya and Iran.
But he recanted this year, saying that his televised confession was forced on him by the government of Pervez Musharraf, the Pakistani president.
Neither Khan nor anyone linked to the case has faced charges in Pakistan and is still seen as a national hero to some in Pakistan for giving the country a safety net against other nuclear-armed states, including neighbouring India.