The Islamabad High Court (IHC) on Tuesday said that white-collar crimes are "not easy to deduct and trace" and therefore, the National Accountability Bureau (NAB) required custody of former president Asif Ali Zardari and his sister Faryal Talpur.

The order also stated that "no mala fide or ulterior motives" were found on NAB's part "which is the core principle for grant or refusal of the bail before arrest".

Last week, the high court had dismissed the applications for a pre-arrest bail by Zardari and Talpur in the fake accounts reference. Following the dismissal, Zardari was arrested by a 15-member NAB team while his sister, Talpur, was taken into custody on June 14. Both PPP leaders are in NAB custody on remand.

Justice Aamer Farooq and Justice Mohsin Akhtar Kayani, who announced the verdict, in their written order issued on Tuesday said that white-collar crimes are "not easy to deduct and trace and cannot be equated with other general offences".

"The accused persons are to be confronted with the documents and inquire about the same repeatedly in order to build up the chain." It stated that for this purpose, the NAB authorities required custody of the petitioners.

According to the order, the legal counsel for the petitioners had argued that since a reference had been filed, NAB Chairman Justice (retd) Javed Iqbal had "no lawful authority" to execute arrest warrants. They had also said that as bonds had been furnished, the petitioners could not be arrested.

The IHC order noted that the furnishing of bonds does not bar NAB from making an arrest regarding an investigation in the case. It stated that the bond is submitted "only for personal appearance" before the court.

According to the order, the argument that the accountability bureau chairman did not have the authority or jurisdiction in the matter was "without substance". The order stated that under Section 24(a) read with Section 24(c) of the National Accountability Ordinance (NAO) 1999, the chairman could issue arrest warrants even after a reference was filed.

It noted that the matter was still being investigated and the reference was just an aspect of the case which had been transferred to an accountability court in Islamabad.

"NAB never really investigated and inquired into the matter and only became seized of it by the direction of the Hon’ble Supreme Court of Pakistan and is still investigating the same," the order read.

"The investigation in the matter is by no means over," it stated, adding: "The prosecuting agency i.e. NAB categorically submitted that money trail is linked with the petitioners and their custody is required for investigation."

Additionally, the IHC judges said that in light of the facts and circumstances "no mala fide or ulterior motives" could be "attributed to the respondent which is the core principle for grant or refusal of the bail before arrest".