Pakistan police fire tear gas at stone-throwing supporters of opposition leader Imran Khan

By Drazen Jorgic and Asad Hashim ISLAMABAD (Reuters) - Pakistani police on Friday fired tear gas at stone-throwing supporters of opposition leader Imran Khan who defied a ban on public gatherings, adding to political deadlock ahead of his plans to shut down the capital next week. There was no immediate report of injuries but TV stations carried footage of police charging with batons, as plumes of tear gas billowed in the air. Police surrounded the home of former cricket hero Khan, who called for nationwide protests after dozens of activists from his Pakistan Tehreek-e-Insaf (PTI) party were arrested a day earlier. The protests have added to the chaos ahead of Khan's plans to lock down the capital on Wednesday in what he described as a final push to force Prime Minister Nawaz Sharif to resign over corruption allegations. Khan had vowed to join Friday's planned rally but had not left his home, with a heavy police presence outside, by the afternoon and was scheduled to hold a press briefing. The rising tensions come at an awkward time for Sharif, with relations between his ruling PML-N party and the powerful military strained over a newspaper leak about a security meeting that angered army officials. Authorities on Thursday swooped on an indoor youth rally by Khan's party in Islamabad, beating activists with batons and detaining 38 people. Police said the rally contravened a city order issued hours earlier to ban all public gatherings in the capital ahead of next week's protests. "Police manhandled our women and our boys. Because of that, Imran Khan has called for nationwide protests," a spokeswoman from PTI's media team said. Khan, who led a weeks-long occupation that paralysed the government quarter of Islamabad in 2014 after rejecting Sharif's decisive election win, has vowed to contest orders banning public gatherings in court but has hinted his supporters would march on the capital next week regardless. A top administrative official in Rawalpindi has also banned protests in the city. Khan had been due to attend a rally for a political ally, Sheikh Rashid of the Awami Muslim League (AML), on Friday afternoon in Rawalpindi. TV footage showed the portly AML leader being ferried to the rally on the back of a motorbike via the back-streets of Rawalpindi. He then climbed on top of a van, shook his fist in the air to supporters and dared police to arrest him. Police have told media they do not have orders for his arrest. Earlier in the day, officials appeared to be resolute that the ban on public gatherings will be enforced, setting PTI on a collision course with authorities. "It is not legal to hold a gathering (in Rawalpindi) right now, so we will try to stop (Khan) if he tries to go there," said Mushtaq Ahmed, the top administrative official in Islamabad. SHUT DOWN SCHOOLS, AIRPORT Khan has warned officials that arresting him would only enrage his supporters and bolster his party's resolve to lock down Islamabad. Authorities blocked main roads leading to the Rawalpindi rally with shipping containers. The rally site also was obstructed by trucks and containers, blocking PTI supporters from gathering en masse. Islamabad Deputy Commissioner Ahmed said PTI would need a permission in the form of a "No Objection Certificate" (NOC) if it plans to host any events, including Wednesday's shutdown strike. "You need an NOC for anything - whether its a media function or a marriage function. Even for a birthday party of more than five people, you need an NOC," he told Reuters. Khan has said next week's protests will bring a million people to the streets. He has said that sit-ins would force the closure of schools, public offices and the main international airport. At the centre of Khan's latest challenge to Sharif's government are leaked documents from the Panama-based Mossack Fonseca law firm that appear to show that Sharif's daughter and two sons owned offshore holding companies registered in the British Virgin Islands. Sharif's family denies wrongdoing. Holding offshore companies is not illegal in Pakistan, but Khan has implied the money was gained by corruption. Khan acknowledged in May that he used an offshore company to legally avoid paying British tax on a London property sale. The ruling party has dismissed Khan's plans to shut down Islamabad as a desperate move by a politician whose popularity is waning ahead of the next general election, likely to be held in May 2018. "Pakistan is going towards becoming a developed country, and the opposition is worried that if this system of development continues until 2018, then by then their politics will be finished," said PM Sharif at a gathering of party workers on Friday. (Writing by Drazen Jorgic; Editing by Nick Macfie)