LAHORE: Punjab Chief Minister Shahbaz Sharif left for London on Sunday where his elder brother and Prime Minister of Pakistan Nawaz Sharif is due to undergo an open heart surgery on Tuesday. The chief minister was also accompanied by his son Hamza Shahbaz and is expected to return on Wednesday or Thursday. The chief minister made an appeal on twitter on Saturday asking his countrymen to pray for the prime minister’s health and speedy recovery. Friends, I request you all to say special prayers for Mian sahib’s health & speedy recovery… – !???????? — Shehbaz Sharif (@CMShehbaz) May 28, 2016 [removed][removed] PM Nawaz is undergoing the surgery at a time when he is caught up in a controversy at home after revelations of Panama Papers which include names of his children, with opposition joining hands to put pressure on the government to come clean on offshore interests of the ruling family. A senior government official has said that it might take a little over a week before the prime minister fully recovers. Sources also quoted the official as saying that none of the expenditures of the medical treatment are going to the state expenditures. Meanwhile the former Chief Justice of Pakistan Iftikhar Muhammad Chaudhry had said that an interim prime minister must be appointed for the time of PM Nawaz’s absence.