Hundreds of Pakistani Christians took to the streets across the country on Sunday, demanding better protection after a Christian neighbourhood was torched in the city of Lahore. The att6ack has been  connected to the country's controversial anti-blasphemy law.

Police fired into the air in Lahore and the country's largest city, Karachi, to try to disperse protesters furious at the arson attack, which caused no casualties and was the result of an allegation of blasphemy.

Rights campaigners say the anti-blasphemy law in Pakistan is widely used against religious minorities, including Christians, Ahmadis and Shi'ite Muslims, usually on flimsy pretexts.

Aside from a Taliban insurgency, U.S. ally Pakistan is facing hardline Sunni groups who are determined to wipe out the Shi'ite minority. Suicide bombings have killed over 200 Shi'ites this year, triggering revenge attacks against Sunnis.

Christian protesters smashed the windows of buses and clashed with baton-wielding police in Lahore in protest at the nearby Saint Joseph Colony neighbourhood being set on fire.

A protest in another Christian neighbourhood of the city turned violent when protesters blocked the main road and attacked vehicles, police said. In Karachi, Christian protesters threw stones at shop windows.

"We tried to disperse them peacefully ... They started throwing stones at police, resulting in several officers receiving injuries," senior Lahore police official Rai Tahir told Reuters.

Elsewhere throughout the Punjab province, Christians held small, peaceful protests.

Punjab's Law Minister condemned the protests: "We will bring the culprits (arsonists) to the gallows ... Christians should not take the law into their hands".

Tahir said more than 150 Muslims were arrested in Lahore of suspicion of torching the homes; they will be tried in anti-terrorism courts. Hundreds of residents had fled their homes, escaping the violence.

In Islam, allegations of blasphemy are treated seriously. Police said two men, one Christian and one Muslim, argued in Lahore on Friday, leading to the Christian being accused of blasphemy. He is reportedly in police custody.

The recent case of a young Pakistani Christian girl accused by a cleric of burning pages of the Koran highlights the danger of the country's anti-blasphemy law for ordinary Pakistanis, including Muslims outside the Sunni majority.