(Recasts with four dead)
By Mubasher Bukhari and Asim Tanveer
LAHORE/MULTAN, Pakistan Aug 9 (Reuters) - Violence erupted in several places in Pakistan on Saturday between police and supporters of an anti-government cleric and at least four people were killed and dozens injured, police and witnesses said.
The violence, which broke out on Friday, is exacerbating tension ahead of a big protest rally by the activist cleric, Tahir ul-Qadri, in the city of Lahore on Sunday.
Qadri is holding the demonstration to protest against deadly clashes between his supporters and police in June but 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. Khan 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 member 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.
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 said.
He said 55 people had been wounded, including 22 police.
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 (200 miles) southwest of the capital, said a doctor.
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.
Qadri, who runs a network of schools, says authorities have also arrested hundreds of his supporters.
"The Punjab police have lost all humanity," he said in a televised speech on Friday. "The rulers have become terrorists."
The government says a few dozen arrests have been made to head off violence. But provincial law minister Rana Mashhood Ahmad told Reuters on Friday that Qadri would be arrested and charged with terrorism offences for inciting violence.
Underscoring the worry about political stability are indications that 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 current prime minister 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)