International: Pakistan approved changes to the constitution on Monday, which included empowering parliament to pick the Supreme Court's chief justice, drawing criticism from opposition parties who said it was an attempt to subvert the judiciary.

Pakistan's top court has become a battleground between the government and jailed former Prime Minister Imran Khan, ruling on issues ranging from a controversial national election to a potential military court trial for Khan and his supporters.

The constitutional changes were approved in an extraordinary session of parliament which was assembled on Sunday, a public holiday, and ran all night, concluding close to dawn on Monday.

"The Chief Justice of Pakistan shall be nominated by the Special Parliamentary Committee...from amongst the three most senior Judges of the Supreme Court," the text of amendment bill, which had a host of other procedural changes, read.

Previously, the Supreme Court's second-most senior judge automatically became the chief justice when the top judge retired at age 65.

"It has been settled that parliament is supreme," Prime Minister Shehbaz Sharif said after his ruling coalition garnered the required two-thirds majority of parliament to amend the constitution for the 26th time since it was passed in 1973.

Pakistani politicians have long complained about judicial overreach into matters of governance, stoking tensions between the judiciary and legislature.

Sharif defended the amendments, saying past verdicts had resulted in the sackings of sitting prime ministers, endorsements of military dictatorships, and the undermining of democracy and parliament.

The current Chief Justice Qazi Faez Isa is due to retire this Friday. There had been concern in government circles that senior judges below him and in the high courts had shown leniency to Khan in a number of cases, analysts say.

Former cricket star Khan, 71, has been in jail for over a year. His 2022 removal from office and subsequent clashes with the military have triggered Pakistan's worst political turmoil in decades.

"It is a black day in our constitutional history and for judicial independence," Gohar Ali Khan, chairman of Khan's Pakistan Tehreek-e-Insaf (PTI), said.