A populist Canada-based cleric returned to Pakistan on Monday to try to start what he has called a "peaceful revolution" against the government, as his supporters engaged in violent clashes with police.
Tahir-ul-Qadri touched down in the eastern city of Lahore after his flight was diverted from Islamabad following violence at the capital's airport that police said left 70 of their officers injured.
Read: Pak SC dismisses Qadri's plea seeking reconstitution of EC
Qadri in January last year drew tens of thousands of people to a sit-in protest in Islamabad. His return comes at a sensitive time for the government, potentially adding to pressure on Prime Minister Nawaz Sharif.
The military is in the midst of a major offensive against Taliban militants in the northwest, and nine people were killed when Qadri's followers clashed with police in Lahore a week ago.
Qadri's supporters, armed with sticks and bricks, clashed with baton-wielding police at Islamabad's airport, where he had been due to arrive on an Emirates flight on Monday morning.
A spokesman for Islamabad police said more than 70 officers were wounded, with several suffering broken bones and head injuries.
The plane was diverted to Lahore "to ensure the safety of the passengers and aircraft", according to a civil aviation official. But for several hours Qadri refused to get off.
The 63-year-old demanded protection from the military before agreeing to disembark. When he left the aircraft he was accompanied by Punjab provincial governor Mohammad Sarwar and opposition politician Chaudhry Pervaiz Elahi.
Emirates said in a statement that all passengers and crew had left the plane and the airline was making arrangements to get travellers to their destination.
Officials with Qadri's Pakistan Awami Tehreek (PAT) movement said he would visit those injured in last week's clashes in hospital before going to his Lahore home to work out a strategy.
Qadri, a religiously moderate cleric who served as a lawmaker under military ruler General Pervez Musharraf, has a substantial following in Pakistan.
But some analysts believe he is also supported by the powerful military establishment to try to keep civilian authorities in check.
He has long urged a "revolution" to overthrow what he calls Pakistan's undemocratic political system, and repeated the call before leaving Britain for Pakistan on Sunday.
Security was tight in Islamabad before his expected arrival there, with the government deploying armed personnel at all entry and exit points of the capital and blocking roads to the airport with shipping containers.
But Qadri's supporters, including a large number of women, managed to breach police cordons to arrive at Islamabad airport overnight, chanting "Long live Tahir-ul-Qadri" and "Revolution, revolution, Islamic revolution".
Surveillance helicopters flew overhead as police fired tear gas at the crowd occupying the area outside the airport, an AFP reporter said.
Qadri had led a sit-in protest lasting over four days while the previous Pakistan People's Party government was in power, four months before it lost the May 2013 general election to Sharif's party.
Qadri had demanded the early dissolution of the PPP government and implementation of a caretaker setup backed by the military and judiciary.
But despite intense media interest, the protest had little long-term impact -- Qadri ended his sit-in after talks with ministers and the election went ahead as planned.
Qadri is the founding leader of Minhaj-ul-Quran International (MQI), an organisation with branches in more than 90 countries which works to promote peace and harmony between communities.
His sudden and apparently well-financed emergence last year after years living in Canada was seen by some analysts as a plot by sections of the establishment - particularly the armed forces - to delay the elections and regain power.