Abdul Qadeer Khan, the scientist who helped Pakistan develop nuclear weapons and allegedly leaked atomic secrets to North Korea, Iran and Libya, was freed from years of de facto house arrest Friday by a high court ruling.

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The United States, which worries that Iran has used Pakistani know-how in pursuit of nuclear arms, said the disgraced scientist's release would be "extremely regrettable."

State Department spokesman Gordon Duguid said Khan remained a "serious proliferation risk." He said the United States was still trying to confirm Khan's official status.

On Friday, a smiling Khan emerged from his house in the Pakistani capital and addressed reporters face-to-face for the first time since 2004.

However, he indicated he would not be discussing Pakistan's atomic bomb program or about who was involved in leaking its secrets around the world.

"We don't want to talk about the past things," he said as the guards who have enforced his long isolation stood aside for a throng of TV crews and journalists.

Khan, the architect of Pakistan's nuclear program, took sole responsibility in 2004 for leaking the nuclear secrets but was immediately pardoned by former President Pervez Musharraf and placed under de facto house arrest. The government insists neither it nor the Pakistani military was aware of his activities.

The 72-year-old scientist, who has suffered a string of illnesses, began agitating for an end to the restrictions after last year's ouster of Musharraf. Over the past year, he has been allowed to occasionally meet friends outside his house and has often spoken to reporters over the phone.

In response to an appeal by his lawyers, the Islamabad High Court declared Khan "a free citizen" on Friday. The court said other details of the order were confidential.

Government prosecutor Amjad Iqbal Qureshi said the decision was the result of a compromise with the government and that "security measures" for Khan would remain. The government has never said that Khan was under house arrest, maintaining he was being held for his own security.

Khan hailed the order as a "good judgment."

"At least I have got my freedom. I can move around," he said.

But his wife said the freedom was limited to the capital and that "more strings have been attached" regarding what he could say. She declined to discuss details, saying that authorities insisted their agreement with her husband remain confidential.

An order issued by the same court last year barred him from discussing the subject of nuclear proliferation even with his relatives.

"We know it is not possible to give our version," Hendrina Khan told The Associated Press by telephone.

A pariah in the West, Abdul Qadeer Khan is lionized by conservatives and Islamists for making Pakistan the world's only Muslim nuclear power and is a hero to many ordinary citizens. One of his first visitors Friday was a senator from the country's most powerful Islamist party.

In phone interviews last year, he complained he had been made a scapegoat and said the army had known all about at least one incident of proliferation — a claim swiftly denied by Musharraf.

Asked Friday what the international community would think of his release, Khan struck a typically defiant tone.

"Are they happy with our God? Are they happy with our prophet? Are they happy with our leader? Never," he said. "I don't care about rest of the world. I care about my country. (President Barack) Obama cares about America, not about Pakistan or India or Afghanistan."

He said he had no plans to return to his former work and wanted to use his new freedom to promote education in Pakistan.

The Foreign Ministry declined to comment on the court order and reiterated the government's determination to avoid fresh controversy about Khan's past.

A ministry statement said the government would provide him with "all requisite security."

It said Pakistan has taken "all necessary measures to promote the goals of nonproliferation. The so called A.Q. Khan affair is a closed chapter."