By Mubasher Bukhari and Asim Tanveer
LAHORE/MULTAN, Pakistan, Aug 10 (Reuters) - Pakistani police registered a murder case on Sunday against an anti-government cleric after three policemen were killed in clashes with his supporters ahead of a demonstration.
The cleric, Tahir ul-Qadri, has called for protests on Sunday, saying he wants to bring down the government by the end of the month because it is corrupt. Another protest, led by opposition politician Imran Khan, is due in the capital on Thursday.
The protests have unnerved the civilian government and raised fears of tension with the military. Some ruling party members believe the protesters are getting support from elements in the military in an effort to weaken the government and stymie its pursuit of policies the military objects to.
The law minister of Punjab province, where the clashes between the clerics' supports and police erupted on Friday, said police were out to arrest him.
"Qadri is responsible for killing police officials and his own workers. Police have booked him for terrorism and murders and will arrest him soon," said the minister, Rana Mashhood Ahmad.
In Pakistan, police must register a case against someone before charging him with a crime.
A spokesman for Qadri said eight of his supporters had been killed and more than a 100 wounded in clashes with police over the past two days.
The nuclear-armed country of 180 million has a history of coups, protests and violent political rivalry though the military denies meddling in politics.
On Sunday, hundreds of Qadri's supporters stood outside his house in the eastern city of Lahore reciting the Koran as a helicopter rattled high over overhead, apparently monitoring the crowd.
The spectre of tension between the civilian government and the military has arisen in particular because of the prosecution for treason of Pervez Musharraf, a former army chief who went on to become president.
Some in the army have privately criticised the legal action against their old boss, who, as army chief in 1999, overthrew the current prime minister, Nawaz Sharif, when he held the office then.
Sharif's government has also made improving relations with India a cornerstone of its policy. But the military is believed to be less keen on such a move towards Pakistan's old enemy and nuclear-armed rival and it sees external relations as its domain.
The government and the military have also disagreed on how to handle Pakistani militants fighting the state.
The violence over the weekend has forced Qadri to change his plan for a big protest in Lahore on Sunday.
Instead, he has called on his supporters to hold protests in their own towns in memory of 14 supporters he said were killed by police in June. They had clashed with police over security barricades around Qadri's house.
The demonstrations are due to begin later on Sunday.
Police say they have arrested more than 500 of Qadri's supporters over the past few days. They dragged many of them from their beds in the middle of the night, activists say.
A week ago, the government deployed the military to protect key installations in the capital. Officials said it was to protect against Taliban attacks but protest leaders say it is an attempt to intimidate them.
Opposition leader Imran Khan is also due to hold a separate protest on Thursday in Islamabad. Khan wants electoral reforms and an investigations into last year's polls, which Sharif won in a landslide victory. (Writing by Katharine Houreld; Editing by Robert Birsel)