Pakistan Prime Minister Imran Khan has vowed to go after the "thieves", who left the country badly in debt and set up a high-powered commission to probe huge debts incurred during the last 10 years, as he defended arrests of several key political figures in corruption cases.

In an unusual midnight speech after the first budget of his cash-strapped government was presented, Khan said that all economic problem were due to debt which increased to Rs 30 lakh crore from Rs 6 lakh crore in 10 years.

His speech came on the day when Leader of the Opposition in the Punjab Assembly, Hamza Shehbaz was arrested by the National Accountability Bureau (NAB) in cases related to money laundering.

On Monday, former president Asif Ali Zardari was also arrested by the NAB in connection with a multi-million dollar money laundering case.

Former Prime Minister Nawaz Sharif (from the PML-N party) is already in jail having been sentenced in another corruption case in 2018.

Khan announced that after putting to rest the initial focus of the government to stabilise the economy, his attention would be more targeted towards bringing the ones to task who had caused the country to fall into such dire straits.

"Pakistan is stable now. That pressure [to stabilise the economy] has been relieved. Now I will go after them [the corrupt politicians]," declared the prime minister.

"I'm making a high-powered enquiry commission with a one-point agenda: how did they raise the debt to Rs24,000 billion (24 lakh crore) in 10 years?" he asked.

He said that the commission shall comprise the FIA (Federal Investigation Agency), IB (Intelligence Bureau), ISI (the Inter-services Intelligence Directorate), FBR (Federal Board of Revenue) and SECP (Securities and Exchange Commission of Pakistan).

The Pakistan Peoples Party and Pakistan Muslim League-Nawaz served in two successive terms since 2008, when Khan claimed debt increased.

Khan said that the commission will include representatives of the Federal Investigation Agency (FIA), Intelligence Bureau (IB), Inter-Services Intelligence (ISI), Federal Bureau of Revenue (FBR) and Security and Exchange Commission of Pakistan (SECP).

He said that those who were in helms of affairs during last 10 years will not be spared.

"All those in power will be fully investigated by this commission which will prepare a report so that no one dare leave the country in tatters ever again," he said.

“Even if my life goes, I will not leave these thieves alone. I had prayed to God to give me one chance — I will not leave them,” he added.

He blamed the two previous governments for all ills including low growth, joblessness and devaluations.

Khan's government has been heavily criticised for the politically-motivated arrests in corruption cases, but he defended them.

Khan said he would not be "blackmailed" with protests.

Talking about the recent arrests of the bigwigs, Khan said: "I am grateful to Allah, the big figures who are now jailed, no one could have imagined [it could be done]."

"People are crying that Sharif and Zardari have been jailed [...] both of them used to call each other corrupt. Mian Nawaz Sharif jailed Zardari twice during his two tenures," he said.

The prime minister said that Nawaz Sharif and Asif Ali Zardari came to an agreement that each would rule for five years and "not say anything to each other".

(PTI)