Opposition politician Shehbaz Sharif submitted his nomination to be Pakistan's next prime minister to the legislature on Sunday, his party said, after incumbent Imran Khan lost a no-confidence vote in parliament after nearly four years in power.

The younger brother of three-times prime minister Nawaz Sharif, Shehbaz, 70, has led a bid by the opposition in parliament to topple former cricket star Khan, and he is widely expected to replace him following a vote on Monday.

The chief of the Pakistan Muslim League-Nawaz (PML-N) had handed in his nomination papers, Marriyum Aurangzeb, a spokeswoman for the party said on Sunday.

Khan, the first Pakistani prime minister to be ousted by a no confidence vote, had clung on for almost a week after a united opposition first tried to remove him.

By dissolving parliament he delayed the vote that he said was part of a foreign-backed plot against him, but the Supreme Court ordered parliament to convene and vote.

Khan's government fell in the early hours of Sunday after a 13-hour session that included repeated delays and lengthy speeches by lawmakers from his Pakistan Tehreek-e-Insaf party.

The vote went ahead after the powerful army chief, General Qamar Javed Bajwa, met Khan, two sources who declined to be identified said, as criticism mounted over the delay to the parliamentary process.

The military has ruled the country of 220 million people for almost half its nearly 75-year history.

Opposition parties were able to secure 174 votes in the 342-member house for the no-confidence motion, giving them the majority they needed to enable Monday's vote to elect a new premier.

Khan has not commented publicly on his ouster but even before the vote, he called for protests.

"I am going to struggle," he said in an address to the nation on Friday.

"I tell all of my supporters across Pakistan, on Sunday, after Isha (evening) prayers, you all have to come out of your homes and protest peacefully against this imported government that is trying to come to power."

'New Dawn'

Shehbaz Sharif, said Khan's departure was a chance for a new beginning.

"A new dawn has started ... This alliance will rebuild Pakistan," he told parliament on Sunday.

Sharif was for years chief minister of Punjab province and has a reputation as an effective administrator. 

His first tasks will be to repair relations with the powerful military as well as ally the United States, and tend to a stuttering economy.

The military viewed Khan and his conservative agenda favourably when he won election in 2018, but that support waned after a falling-out over the appointment of the influential military intelligence chief and economic troubles that led to the largest interest rate rise in decades this week.

Khan had antagonised the United States throughout his tenure, welcoming the Taliban takeover of Afghanistan last year and more recently accusing the United States of being behind the attempt to oust him. Washington dismissed the accusation.