New York, Nov 24: Disturbing evidence of a secret nuclear alliance between Pakistan and North Korea has emerged with US intelligence agencies tracking a Pakistani cargo aircraft that landed at a North Korean airfield and took on ballistic missile parts, a media report said on Sunday.

American spy satellites recorded images of the American-built C-130 aircraft making the sortie in July, New York Times reported. Several times since, American intelligence agencies watched silently as Pakistan's air fleet conducted a deadly barter with North Korea, it said.

While Pyongyang provided Islamabad with missile parts it needs to build a nuclear arsenal capable of reaching strategic sites in India, Pakistan provided the North with many of the designs for gas centrifuges and much of the machinery it needs to make highly enriched uranium for the communist nation's latest nuclear weapons project, the daily said. In interviews with the Times over the past three weeks, officials and experts in the United States, Pakistan and South Korea described a relationship between North Korea and Pakistan that now appears much deeper and more dangerous than the US and its Asian allies first suspected. They described how, even after Pakistan President Pervez Musharraf sided with the US in the fight against terrorism, his country's secretive A Q Khan Nuclear Research Laboratories continued its murky relationship with the North Korean military. Bureau Report