Leader of the Opposition Shahbaz Sharif, while addressing a session of the National Assembly today, asked who had asked for an NRO.
The PML-N president asked Prime Minister Imran Khan to elaborate on the name of the person who had asked for an NRO, and when such an incident had occurred.
Shahbaz added that if the premier could prove he had asked for an NRO, he would quit politics forever.
"I am a servant of Pakistan, I won't take any u-turn," Shahbaz said.
The PML-N president also took aim at the government's decision to increase gas and electricity prices.
He alleged that the government had come to power through a rigged election and had lost credibility in the eyes of the public in a very short time.
The Leader of the Opposition referred to PM Khan as an "absconder", and criticised him for not coming to the House.
Shahbaz pointed out that although PM Khan had claimed he would come to the NA to respond to statements like the British premier, he had not stuck to his word.
He said that there was an "unholy alliance" between the National Accountability Bureau (NAB) and Pakistan Tehreek-i-Insaf (PTI).
The PML-N leader added that PM Khan had previously also been accused by NAB and inquired in what capacity the body's chairman had met the premier.
He asked if the NAB chairman had met PM Khan in the capacity of a suspect or as the Leader of the House, and said that if it was as a suspect then he should also meet Shahbaz in jail.
The PML-N leader criticised NAB for issuing a fresh list of those who were facing investigations.
Shahbaz added that he wasn't afraid of jails, as he and his family had faced such situations in the past as well.
Addressing the NA for the first time, PPP co-chairman and former president Asif Ali Zardari said that he was addressing the house as a member after 20 or 25 years.
He said that they [PPP] had accepted the government of Nawaz Sharif begrudgingly and now begrudgingly had also accepted the PTI government.
Zardari addresses National Assembly for the first time
Zardari added that questions about fairness of elections also arise in the United States and the United Kingdom, but the solution lies in democracy alone.
"We should all sit together and prepare a long-term plan for the next 20 to 25 years to bring the country out of the present crisis."
He added that in the way that they [PPP] had been ready to work with Nawaz Sharif's government, they were also ready to support this government.