Faryal Talpur (centre) arrives to appear in a court in Karachi. File / AP

Earlier this week, Zardari was also apprehended by the NAB in the same case.

A five-member NAB team including female investigators visited the Zardari House in Islamabad, which was notified as a sub-jail by the NAB chairman "for the purposes of detention of accused,” according to a notification issued by the accountability watchdog.

Zardari was arrested on Monday after cancellation of his pre-arrest bail by the Islamabad High Court (IHC) in the fake bank accounts case, prompting a strong reaction from the opposition and sporadic protests by PPP workers in various parts of the country, mostly in Sindh.

The NAB said the grounds for arresting Zardari included whitening ill-gotten money through fake accounts, acquiring stakes in Summit Bank through fraudulent means, using Omni Group as a hedge between himself and fake accounts, receiving millions of rupees from two fake accounts, and getting unauthorised payments released for construction of a Karachi plot.

Zardari is currently on physical remand in NAB custody. NAB investigators and after their questioning of Zardari, and concluded that Talpur's arrest was "unavoidable".

Talpur will be produced before an accountability court on Saturday to seek her physical remand.

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.

The government has denied any role in the arrest of Zardari and says the NAB operates independently. But the crackdown has prompted an angry response from PPP officials, including Zardari's son, Bilawal Bhutto Zardari.

"We will have to go out into the streets and show people how their rights are being taken away," Bhutto Zardari told a hastily called news conference. "We can see in these days that the rule of law is not being applied."

As well as Zardari, former prime minister Nawaz Sharif is also in jail on corruption charges.

Tariq Butt / Reuters