Anti-government protesters in the country blocked a key highway linking the country to Afghanistan on Wednesday, as part of what they called the "second phase" of action aimed at ousting Prime Minister Imran Khan.

The protests, led by Maulana Fazl-ur-Rehman, head of the conservative Jamiat Ulema-i-Islam (F) party, began with the "Azadi" March on Oct. 27 from Karachi.

Tens of thousands of protesters reached Islamabad on Oct. 31, where they were holding a sit-in on its main highway demanding Khan's resignation and a fresh election, over allegations of electoral fraud and mismanagement of the economy - accusations the government denies.

JUI-F workers holding party flags blocked the Quetta-Chaman highway in the west of the country with a sit-in on Wednesday, resulting in a long queue of trucks laden with goods, footage from private news channels showed.

"I announce 'Plan B' from tomorrow," Rehman said in a speech to supporters in Islamabad on Tuesday night.

The plan envisages blocking several of Pakistan's highways and eventually a countrywide lockdown, Akram Durrani, a senior figure in JUI-F, previously told reporters.