Lahore: Islamist groups are stepping up sectarian attacks in Punjab, Pakistan's largest and wealthiest province, to try and further destabilise the US ally already battling Al Qaida and the Taliban, analysts say.

Over the past two months, Sunni Muslim affiliated with both Islamist militant groups have increased their attacks on adherents of opposing schools of Islam in Punjab.

In May attacks that killed more than 80 people, militants targeted two Lahore mosques of the Ahmadi sect, who consider themselves Muslims but who Pakistan has declared as non-Muslims.

A month later, militants attacked the Data Darbar, the Sufi shrine for Pakistan's most popular Muslim saint, killing 42 people.

And in mid-July, a suicide bomber attacked a Shiite mosque in Sargodha, wounding 15 people.

Analysts say the Punjab strikes share a common strategy: radical Sunni groups are trying to provoke Pakistan's various sects to hit back in an attempt to inflame civil unrest.

Cause for concern

Punjab has traditionally been the powerbase of Pakistan's ruling establishment.

The nuclear-armed South Asian country is considered vital to US efforts to stabilise Afghanistan, so any instability in Punjab — and thus in Pakistan — is a cause for great concern for the United States.

Instability could also impact military operations against militants in the northwest provinces bordering Afghanistan.

"The sectarian militant groups are now becoming more active in Punjab," said security and political analyst Hassan Askari Rizvi. "These groups now want to create social unrest by fanning sectarian violence in the country."

"It seems to be an attempt by militants to divert attention from operations in the northwest by opening a new front for the government to tackle."

Sectarian violence in not new to Pakistan, particularly in Punjab, which has been a hotbed of hostility between Sunni and Shiite militants for decades.

In the 1990s, hundreds were killed in Sunni-Shiite sectarian violence there.

These incidents decreased after the US-led war in Afghanistan, as militant groups focused their attention on fighting Western forces across the border and, later, the Pakistani military in the northwest.

Punjabi militant groups, some of which have been fighting Indian troops in the disputed region of Kashmir, have splintered and forged ties with Al Qaida over the years, officials say.