Mr Sharif used his speech to say Mr Khan’s allegations were a “lie, drama and fraud”, but he would hold a special session of parliament attended by military and intelligence chiefs and top diplomats to investigate.

“The nation should know whether they have been lied to,” Mr Sharif said. If any evidence of a foreign conspiracy was found “I will go home”, he added.

Mr Sharif, the younger brother of Mr Khan’s predecessor, Nawaz Sharif, also announced several populist measures in his speech. He promised a new minimum wage of 25,000 rupees (around £100), pay rises for civil servants, and development projects in rural areas.

He spent three terms as chief minister in Punjab province, where he acquired a reputation as a tough and competent administrator. He is also on bail as part of a money-laundering investigation, though he denies wrongdoing and says the investigation is politically motivated.

His abilities are likely to be sorely tested by Pakistan’s economic crisis, which has seen the rupee slide for nearly a year, debt grow, inflation climb and the balance of payments worsen.