Twenty one of those deaths were the result of a mass execution of men working for a paramilitary unit who were kidnapped last week. Another 20 died in an attack on 3 busses carrying Shia pilgrims from Pakistan to Iran.

Daily Star:

Pakistani militants, who have escalated attacks in recent weeks, killed at least 41 people in two separate incidents, officials said on Sunday, challenging assertions that military offensives have broken the back of hardline Islamist groups.

The United States has long pressured nuclear-armed ally Pakistan to crack down harder on both homegrown militants groups such as the Taliban and others which are based on its soil and attack Western forces in Afghanistan.

In the north, 21 men working for a government-backed paramilitary force were executed overnight after they were kidnapped last week, a provincial official said.

Twenty Shiite pilgrims died and 24 were wounded, meanwhile, when a car bomb targeted their bus convoy as it headed toward the Iranian border in the southwest, a doctor said.

New York-based Human Rights Watch has noted more than 320 Shias killed this year in Pakistan and said attacks were on the rise. It said the government's failure to catch or prosecute attackers suggested it was "indifferent" to the killings.

Pakistan, seen as critical to U.S. efforts to stabilise the region before NATO forces withdraw from Afghanistan by the end of 2014, denies allegations that it supports militant groups like the Afghan Taliban and Haqqani network.

Afghan officials say Pakistan seems more genuine than ever about promoting peace in Afghanistan.

At home, it faces a variety of highly lethal militant groups that carry out suicide bombings, attack police and military facilities and launch sectarian attacks like the one on the bus in the southwest.

Witnesses said a blast targeted their three buses as they were overtaking a car about 60 km (35 miles) west of Quetta, capital of sparsely populated Baluchistan province.

"The bus next to us caught on fire immediately," said pilgrim Hussein Ali, 60. "We tried to save our companions, but were driven back by the intensity of the heat."

Twenty people had been killed and 24 wounded, said an official at Mastung district hospital.

International attention has focused on al Qaeda and the Pakistani Taliban.

But Pakistani intelligence officials say extremist Sunni groups, lead by Lashkar-e-Jhangvi (LeJ) are emerging as a major destabilising force in a campaign designed to topple the government.

Their strategy now, the officials say, is to carry out attacks on Shiites to create the kind of sectarian tensions that pushed countries like Iraq to the brink of civil war.

Some of those extremist Sunni groups are on the payroll of Pakistan's intelligence service, the ISI. India pointed to Lashkar-e-Taiba as the culprits behind the Mumbai Massacre in 2008 - an organization that was allowed to train and operate freely in Pakistan. Other terrorist groups operate in the disputed Kashmir region, also hitting targets in India proper.

But days like yesterday show how blowback from those operations can cost Pakistan dearly. It probably won't deter them from further support of the Afghan Taliban and Haqqani network - both groups killing Americans in Afghanistan - but it might make them rethink some of their support for local terrorists who are as eager to kill Shias as they are foreigners.