The anti-graft watchdog had taken Safdar in its custody after he along with his wife, Maryam Nawaz landed at the Benazir Bhutto International Airport late Sunday night.
The accountability court had issued non-bailable arrest warrants for Safdar and other members of the family, including Hussain and Hassan Nawaz, after they failed to appear in the court despite summons in London flats reference.
It is important to mention that parliamentarians cannot be arrested without prior permission from either the speaker NA or the Senate chairman.
Talking to media during visit of his constituency NA-120, the speaker said the Islamabad police will be required to get prior permission from him before arresting PTI chief Imran Khan.
The Election Commission of Pakistan has issued non-bailable arrest warrants for Imran Khan for his production on October 26 in a contempt case.
However, the PTI has also challenged the warrants in the Islamabad High Court. The court would take up the case on Friday.