* Qadri urges supporters to demonstrate in home towns
* Police say around 500 of his supporters arrested
* Planned demonstrations unnerve government (Adds large rally cancelled)
By Mubasher Bukhari and Asim Tanveer
LAHORE/MULTAN, Pakistan Aug 9 (Reuters) - Violence flared in several towns and cities in Pakistan on Saturday between police and supporters of an anti-government cleric, killing at least four people and injuring scores, police and witnesses said.
Activist cleric Tahir ul-Qadri called off a large protest rally planned in Lahore on Sunday. Following a police crack down, he urged supporters to hold smaller protests in their home towns instead.
"Pick up the bodies of the martyred and keep the bodies of the injured before you - but protest peacefully," Qadri said in a televised address. "The government wants a massacre in the name of a crackdown."
The violence, which started on Friday, exacerbated tensions ahead of the Lahore demonstration. Qadri had planned to protest against deadly clashes between his supporters and police in June.
He has also condemned the government as corrupt and called for the overthrow of Prime Minister Nawaz Sharif.
A separate protest, led by opposition politician Imran Khan, is planned for the capital on Thursday to protest alleged election irregularities. He has also called for the government to go.
The planned demonstrations have unnerved Sharif's fledgling civilian government. The nuclear-armed nation of 180 million has a history of coups and street protests.
Some members of the ruling party fear the protesters may be getting support from elements in the powerful military, which has had a series of disagreements with the government. The military denies meddling in politics.
Security was tight in Lahore on Saturday with police manning checkpoints throughout the eastern city, the home town of both Qadri and the prime minister, and the capital of Punjab, the country's richest province.
Around 500 Qadri supporters had been arrested, said Nabeela Ghazanfar, the provincial police spokeswoman, and more than 100 police injured. The paramilitary Rangers force patrolled the streets.
Rahiq Abbassi, a spokesman for Qadri, said more than a hundred of their supporters were also injured and denied they had attacked the police.
In several parts of Punjab, police tried to block Qadri's supporters from travelling to Lahore, sparking confrontations and violence, police and witnesses said.
Two men and a woman were killed in the district of Gujranwala, about 220 km (140 miles) southeast of Islamabad, said deputy inspector general of police Saad Bahrwana.
Shopkeeper Muhammad Hussain said those clashes began when police tried to stop Qadri supporters from travelling to Lahore.
Another man was shot dead during clashes between Qadri supporters and police in the town of Bhakkar, 320 km southwest of the capital, said a doctor.
Police said a police station had been burnt down and dozens of weapons seized in the central town of Qaidabad.
In Lahore, Qadri's supporters on Friday tried to remove barricades that authorities put up around Qadri's house, sparking clashes.
The supporters brought a crane to move shipping containers blocking off the residence and threw stones at police who tried to stop them by firing teargas. Police withdrew and women activists armed with batons surrounded Qadri's house.
The clashes continued through Friday night into Saturday.
Provincial law minister Rana Mashhood Ahmad told Reuters on Friday Qadri would be arrested and charged with terrorism offences for inciting violence.
Underscoring the worry about political stability are indications the military is frustrated with the government. Some officers are unhappy after former military chief and ex-President Pervez Musharraf was put on trial for treason last year.
Musharraf deposed Sharif, in a coup in 1999 but was forced to step down in 2008. Sharif returned from exile shortly afterwards and won a landslide victory in last year's polls.
There was also disagreement between the government and the army on how to handle militants attacking the state, with the army favouring military action and the government holding out hope for peace talks. The army eventually won the argument and launched an offensive in June.
The military has ruled Pakistan for about half its history but is generally seen as reluctant to seize power and take on responsibility for a struggling economy and other problems. But excessive violence on the streets could force the military to step in to restore order.
Last week, the government deployed the military around key installations in Islamabad and on Friday it banned gatherings of more than five people in the city. (Additional reporting by Mehreen Zahra-Malik in Islamabad; Writing by Katharine Houreld; Editing by Robert Birsel and Sophie Hares)