Pakistani opposition leader Shahbaz Sharif was ordered jailed for 10 days yesterday after being arrested in a corruption case, his lawyer said, meaning he will not be able to campaign for his party ahead of crucial by-elections next week.

Sharif is the younger brother of ousted Prime Minister Nawaz Sharif, who was sentenced earlier this year to 10 years in prison by an anti-corruption court after the Supreme Court removed him from power.

Friday's arrest of Shehbaz by agents of the National Accountability Bureau (NAB) in Lahore involved a case of alleged corruption in a low-cost housing scheme when Sharif was chief minister of Punjab province.

A NAB court yesterday heard charges that Sharif in 2014 illegally cancelled a contract with a construction company and sought to award it to another company, allegedly for a bribe.

The court ordered him remanded in custody for 10 days to be interrogated.

Hundreds of activists from Sharif's Pakistan Muslim League-Nawaz gathered outside the court, chanting pro-Sharif slogans as police and army Rangers guarded the venue.

Shahbaz's lawyer said that Sharif was improperly arrested on a warrant that was kept secret. Sharif went to the court for questioning in another corruption case involving a water purification scheme but instead was arrested on the housing project warrant.

"They cannot arrest the leader of the opposition in this manner," the lawyer said.

Ex-premier Nawaz Sharif was arrested 10 days before the July 25 general election, which was won by cricket star turned politician Imran Khan, who now leads the new government. He was released from prison last month pending an appeal.