An NAB spokesman said Faryal Talpur had been ordered to remain in her house. He said she would be attended by female police officers and her treatment should not be described as an arrest.
'Time for nation to stop glorifying money launderers who have damaged our nation & impoverished our people and now seeking refuge behind 'democracy.'
The decision paves the way for the country's anti-graft body to arrest the two, perhaps within hours.
Reports said Imran's visit cost the national kitty $67,180 against $752,688 spent by Zardari on his visit in 2009 and $549,853 by Sharif on his visit to the US in 2013.
The development came about five months after Zardari, the widower of the country's assassinated former Prime Minister Benazir Bhutto, was arrested by Pakistan's anti-graft body in a multi-million dollar money laundering case.