Shehbaz Sharif becomes Pakistan's new prime minister

Shehbaz, brother of former prime minister Nawaz Sharif, received 174 votes in the 342-member lower house of parliament.

The 70-year-old leader enjoys the backing of the multi-party Pakistan Democratic Movement (PDM) and is seen as an able administrator.

The former ruling party Pakistan Tehreek-e-Insaf (PTI), which has demanded early elections, decided to quit the house en masse.

"The parliamentary party has decided to resign from the assemblies against the imported government," PTI official Farrukh Habib said.

Imran and his party say their government's collapse was engineered by the United States with local collusion, a charge denied by the US administration.

Political analysts expect Imran to increase pressure on the new government to force an early general election as the PTI has seen a surge in public support following its ouster on Saturday night in a Supreme Court-directed parliamentary vote of no-confidence.

Resigning en masse from parliament would help Imran further strengthen his political credentials and make things difficult for the new government, former diplomat Abdul Basit said in a social media post.

"This is a bold decision and in line with his public posturing," he said.

The PTI had earlier nominated former foreign minister Shah Mahmood Qureshi against Shehbaz, but eventually boycotted the session held to elect the new prime minister.

Deputy speaker Qasim Khan Suri, who was in the speaker's chair when the session began, also got up and left the house when Qureshi announced the boycott at the end of a speech.

Shehbaz is a former chief minister of Punjab province, home to more than half of Pakistan's 220 million population.

He has cordial relations with Pakistan's powerful military.