A 24-hour strike organised by Sunni Muslim clerics is taking place across Pakistan to protest against possible changes to blasphemy laws.
Rallies were staged in Islamabad, Lahore, Karachi, Peshawar and Quetta after Friday prayers.
The government has distanced itself from a bill to change the law, which carries a mandatory death sentence for anyone who insults Islam.
Rights groups say the law is often used to persecute religious minorities.
The legislation returned to the spotlight in November when a Pakistani Christian woman, Asia Bibi, was sentenced to death.
Although no-one convicted under the law has been executed, more than 30 accused have been killed by lynch mobs.
'Over our dead bodies'
The Pope has led international calls to show mercy on Ms Bibi, who denies insulting the Prophet Muhammad during an argument with other farmhands in a Punjab province village in June 2009.
Friday's strike saw businesses shuttered and transport workers walking out in towns and cities across the country.
There was no public transport in the southern city of Karachi, where demonstrators blocked traffic as part of the industrial action.
The BBC's Ilyas Khan says bus owners in the Sindh province capital may have feared their vehicles could be torched if put on the road.
Quetta, the capital of the southern province of Balochistan, also ground to a halt.
There was a partial shutdown in the national capital of Islamabad, the north-western city of Peshawar and Lahore, capital of Punjab.
One Sunni cleric in Islamabad warned in his Friday sermon that any change to the blasphemy law would happen "over our dead bodies".
The strike was held to protest against a private member's bill submitted to parliament.
It seeks to amend the law by abolishing the death sentence and by strengthening clauses which prevent any chance of a miscarriage of justice.
The bill has been drafted by a member of the ruling Pakistan People's Party and by a former Information Minister, Sherry Rehman.
This led religious groups, who are demanding that Ms Rehman quit, to conclude the government was behind it.
On Wednesday, Pakistan's religious affairs minister told parliament the bill did not reflect government policy.
"I state with full responsibility that the government has no intention to repeal the blasphemy law," Syed Khurshid Shah said.
"If someone has brought in a private bill, it has nothing to do with the government."
Federal Law Minister Babar Awan told reporters that Friday's strike was simply the latest attempt to revive a once powerful alliance of religious parties.
The Muttahida Majlis-e-Amal emerged as the third largest vote-winner in the 2002 elections held by the regime of President Pervez Musharraf, but the grouping had broken apart by the time of polls two years ago.
Our correspondent says the government is hoping to placate shrill religious protest at a time when it is in difficulty with two coalition partners.
The Muttahida Qaumi Movement this week withdrew two ministers from the federal cabinet, blaming corruption and rising prices.
The Jamiat-i-Ulema Islam party, a smaller coalition partner, withdrew from the government earlier in December after one of its ministers was sacked.
Many believe the two parties are acting at the behest of the security establishment to undermine the country's political system.