Shehbaz Sharif was voted in as Pakistan's prime minister for a second time on Sunday, presiding over a shaky alliance that has shut out followers of jailed opposition leader Imran Khan.

Newly sworn-in lawmakers in Pakistan's National Assembly elected Sharif by 201 votes, three weeks after national elections marred by widespread allegations of rigging.

"Shehbaz Sharif has been declared to have been elected as prime minister of Islamic Republic of Pakistan," said newly appointed speaker of the National Assembly Sardar Ayaz Sadiq.

Omar Ayub Khan stood against Sharif as the candidate of choice for MPs loyal to Khan, gaining 92 votes.