Gunmen have launched simultaneous raids on two mosques of the minority Ahmadi Islamic sect in Lahore, killing more than 80 people, Pakistani police say.

The attackers fired guns and threw grenades at worshippers during Friday prayers. Three militants later blew themselves up with suicide vests.

Pakistani forces have secured both buildings, but are still searching for militants who fled the scene.

Lahore has been the scene of a string of brazen attacks.

It is unclear who carried out the attacks, but suspicion has fallen on the Pakistani Taliban, Ali Dayan Hassan of Human Rights Watch told the BBC.

Mr Hassan said the worshippers were "easy targets" for militant Sunni groups who consider the Ahmadis to be infidels.

Suicide vests

Police said several attackers held people hostage briefly inside the mosque in the heavily built-up Garhi Shahu area.

AT THE SCENE The attackers shot anyone who moved, according to survivors like Syed Rashid Rahim, a lawyer we interviewed at the hospital. He survived three hours trapped in the mosque, and three bullet wounds. The hardest thing to bear, he said, was the brutal killing of a boy aged 13 or 14, which happened in front of his eyes. His father was behind him, sheltering behind a column. He asked him for water and the son was offering him water. While he was drinking, these two people came in and they shot him point blank. "I cannot forget that," he said, fighting back tears. "I thought they would spare him, but they did not."

Some took up positions on top of the minarets, and fired assault rifles at police engaged in gunfights with militants below.

Three of the attackers blew themselves up with suicide vests packed with explosives when police tried to enter the mosque, officials said.

Police were searching for at least two militants who managed to flee the scene.

Police took control of the other mosque in the nearby Model Town area after a two-hour gunfight.

Gunmen opened fire indiscriminately at the mosque, before security forces managed to kill one militant and capture two others, eyewitnesses told the BBC.

They were said to be armed with AK-47 rifles, shotguns and grenades.

Persecuted minority

Sectarian attacks have been carried out by various militant groups in Punjab province, and across Pakistan in the past.

While the Ahmadis consider themselves Muslim and follow all Islamic rituals, they were declared non-Muslim in Pakistan in 1973, and in 1984 they were legally barred from proselytising or identifying themselves as Muslims.

WHO ARE THE AHMADIS? A minority Islamic sect founded in 1889, Ahmadis believe their own founder, Mirza Ghulam Ahmad, who died in 1908, was a prophet

This is anathema to most Muslims who believe the last prophet was Muhammad, who died in 632

Most Ahmadi followers live in the Indian subcontinent

Ahmadis have been the subject of sectarian attacks and persecution in Pakistan and elsewhere

In 1974 the Pakistani government declared the sect non-Muslim Who are the Ahmadis? In pictures: Lahore attacks Analysis: Soft target for militants Eyewitness: Mosque attack

Members of the community have often been mobbed, or gunned down in targeted attacks, says the BBC's M Ilyas Khan in Islamabad.

But this is the first time their places of worship have suffered daring and well co-ordinated attacks that bear the mark of Taliban militants, our correspondent adds.

The London-based Ahmadi association said the attacks were the culmination of years of "unpoliced persecution" against the Ahmadis.

"Today's attack is the most cruel and barbaric," the Ahmadiyya Muslim Community UK said in a statement.

The Chief Minister of Pakistan's Punjab province, Shahbaz Sharif, expressed "heartfelt sorrow" over the killings.

"No condemnation, however strong, will be enough for these incidents," he said.

US state department spokesman Philip Crowley said Washington also condemned the "brutal violence against innocent people".