By Haroon Rashid
BBC Urdu service, Islamabad
Dr Khan stunned the world with his confession
The family of disgraced Pakistani nuclear scientist AQ Khan say it is not clear whether his de facto house arrest has been permanently relaxed.
On Wednesday Dr Khan was allowed to make a rare trip from his Islamabad home to Pakistan's Academy of Sciences.
His wife, Henny, told the BBC her husband went to pay his respects after the death of a colleague.
Dr Khan caused a scandal when he confessed to passing nuclear technology to Libya, Iran and North Korea in 2004.
'Cup of tea'
Henny Khan told the BBC her husband was very happy to be out and about.
"But we don't know whether this was just a one-time relaxation or a change in the government's policy. Though he was very careful that nobody knows about the visit."
Dr Khan himself headed the academy for six years.
Officials there said they were surprised to find him amongst them.
"He just came and had a cup of tea with me," the academy's treasury secretary, Dr Misbahuddin Shami, told the BBC.
Mrs Khan said her husband was now allowed to see seven or eight friends and his daughter on a regular basis.
Pakistan's military was unable to clarify whether the relaxation of the terms of the scientist's detention was permanent.
A spokesman said the interior or foreign ministries should be contacted.
However, Interior Secretary Syed Kamal Shah said his ministry neither imposed the restrictions nor lifted any.
Many believe the relaxation could be the result of the change in government in Pakistan, where a civilian administration took power following elections earlier this year.
In April, Foreign Minister Shah Mehmood Qureshi cited Dr Khan's age - he is over 70 - and poor health to argue that he should be allowed to leave his Islamabad villa to meet friends and visit restaurants.
Dr Khan had surgery in the southern city of Karachi for prostate cancer in 2006.