Shahbaz Sharif, head of the Pakistan Muslim League party, was detained in the eastern city of Lahore by the National Accountability Bureau (NAB) after a court cancelled his bail.

Shahbaz, who is the younger brother of former prime minister Nawaz Sharif, stands accused of money laundering and accumulating wealth beyond his known sources of income, the NAB said in a statement.

He has not yet commented on the allegations.

Sharif was the chief minister of Pakistan's largest province of Punjab until 2018 and is currently head of the parliamentary opposition.

His elder brother, Nawaz Sharif, is being treated in London for a heart condition. A court has also cancelled his bail.

Sharif was previously arrested in October 2018 on corruption allegations but was released in February 2019 when a court approved his bail.

Shahbaz Sharif's arrest comes days after 11 opposition parties formed an alliance and said they planned to launch an anti-government movement with rallies beginning in October.

"This is out of government's fears of opposition planned rallies," said Marriyum Aurangzeb, spokeswoman for Sharif's party.

Several opposition leaders, rights activists and journalists have been arrested in Pakistan since the government of Prime Minister Imran Khan took power following controversial elections in 2018 which were marred by allegations of interference by the powerful military.

Australian Associated Press