A Pakistani court declared disgraced nuclear scientist Abdul Qadeer Khan free on Friday, apparently ending five years of house arrest for the man at the center of the world's most serious proliferation scandal. Khan, lionized by many Pakistanis as the father of the country's atomic bomb, confessed to selling nuclear secrets to Iran, North Korea and Libya in 2004, but was immediately pardoned by the governemnt, although his movements were restricted to effective house arrest. “It's a matter of joy. The judgment, by the grace of Allah, is good,” Khan told reporters outside his Islamabad house soon after news of the High Court ruling broke. “It is because of this judgment that I am speaking to you,” said the 72-year-old scientist, who has been treated for prostate cancer. It was not immediately clear to what extent security agencies would lift restrictions on his movements. His detention had been relaxed over the past year and he had been allowed to meet friends and had traveled to the city of Karachi at least once under tight security. Khan had also given a series of interviews to media after a new government came to power last March but was barred from speaking to reporters by a July court ruling. Government prosecutor Amjad Iqbal Qureshi said “security measures” for Khan would remain in place, suggesting some restrictions would remain. Khan's lawyer said the High Court had declared him a free citizen. “The court has said as he was not involved in nuclear proliferation or criminal activity, there is no case against him, therefore, he is a free citizen,” lawyer Ali Zafar told Geo News television. The US State Department said on Friday that Khan's release would be “extremely regrettable” and “unfortunate.” Spokesman Gordon Duguid told reporters that Khan remains a “serious proliferation risk.” Last year, a UN nuclear watchdog said Khan's network smuggled nuclear blueprints to Iran, Libya and North Korea and was active in 12 countries. Last month, the US State Department said it had imposed sanctions on 13 individuals and three private companies because of their involvement in Khan's network. Pakistan has never let foreign investigators question Khan, saying it had passed on all relevant information about his nuclear proliferation. Pakistan regards the case as closed, but US and international nuclear experts investigating proliferation still want to question him. The 72-year-old said he was proud of what he had done for Pakistan, in making it safe from India, and said he had no need to answer to any foreign government. “I will always be proud about what I did for Pakistan,” he told reporters. “I am obliged to answer only to my government not to any foreigners,” he said. Khan said he was finished with his nuclear work and wanted to devote his time to education. He said he had no plan to travel abroad apart from Makkah for a pilgrimage.