Senator Raza Rabbani on Thursday demanded that the government explain in Senate in an in camera briefing why an unexplained, but significant sum of money was sanctioned for Inter Services Intelligence, as revealed in the federal budget for fiscal 2018-19.

The ISI chief, according to the Miftah Ismail-announced budget, was reportedly given access to Rs4.5 billion for a "special assignment", which Rabbani wants more details about.

"The DG ISI was given funds for a special assignment," Rabbani said during the Senate session on budget today. "When quizzed over this during a press conference, [the government] said such details cannot be disclosed in public.

"We are not asking about other expenses but what do they mean by a 'special assignment'? This needs to be explained," he said.

"The parliament should be taken in confidence over this payment," he added.

Rabbani also took note of the marked increase in defence expenditure for the upcoming year, saying: "This government has blown the federation to smithereens. The defence budget was increased by 20 per cent on the federal government's recommendations.

Read: Ministry justifies defence budget hike

"This budget of Rs1.1 trillion does not even reflect pension payments," he observed.

Rabbani, in his speech, also questioned if increasing the defence and federal expenditures have had any affect on the National Finance Commission (NFC) award.

"Is it due to these increased expenditures that the NFC award is not being implemented?" he asked, before adding: "For a fourth budget to come without an NFC award is unfortunate."

The former Senate chairman further complained that "there was neither a need for this budget nor a three-to-four-month budget, as the caretaker setup would have had the authority to take finance-related decisions."

Meanwhile, media persons present at the upper house to cover the session staged a boycott in protest over the police's violence against journalists earlier in the day.

Correction: This story initially incorrectly stated that Senator Rabbani had asked the DG ISI to explain the funds made available to him as revealed in the federal budget. The explanation was, in fact, sought from the government. The error is regretted.