Pakistani police have filed terrorism charges against former prime minister Imran Khan, escalating political tensions in the country amid mass rallies for his return to office.

The terrorism charges come over a speech Mr Khan gave in Islamabad in which he vowed to sue police officers and a female judge, and alleged a close aide had been tortured after his arrest.

Mr Khan himself appeared to still be free and had not immediately addressed the police charge sheet being lodged against him.

Pakistan's opposition Tehreek-e-Insaf party, Mr Khan's political party, published videos online showing supporters surrounding his home to potentially stop police from reaching it.

Mr Khan came to power in 2018, promising to break the pattern of family rule in Pakistan.

His opponents have contended he was elected with help from the powerful military, which had ruled the country for half of its 75-year history.

After being ousted by a no-confidence vote by the Pakistani parliament in April, Mr Khan alleged without providing evidence that the military took part in a US plot to oust him.

Washington, the Pakistani military and the government of Mr Khan's successor, Prime Minister Shahbaz Sharif, have all denied the accusation.

Mr Khan has been carrying out a series of mass demonstrations, trying to pressure Mr Sharif's government.

The internet-access advocacy group NetBlocks said internet services in the country blocked access to YouTube after Mr Khan broadcast a live speech on the platform.

The broadcast was made despite a ban issued by the Pakistan Electronic Media Regulatory Authority.

AP