Kurram, which borders Afghanistan, has been plagued by violence between Shia and Sunni tribes [Reuters]

A suicide attacker on a motorcycle has blown himself up close to a mosque in northwest Pakistan, killing at least 26 people and wounding scores more in an attack claimed by the Taliban.

The bomber detonated his explosive vest outside a mosque after Friday prayers in a Shia Muslim neighbourhood in the Kurram tribal region, near the Afghan border, government officials said.

Three more people were killed when police shot at protesters from the Shia community after the bombing in Parachinar, the main town in Kurram, an official said. A curfew was later imposed in Parachinar.

The blast destroyed shops in the market, trapping some people, Wajid Ali, a local government administrator, said.

Hospital sources put the death toll at 26, with 37 others wounded.

Fazal Saeed, the leader of a breakaway faction of the Pakistani Taliban, claimed responsibility for the attack.

"We have targeted the Shia community of Parachinar because they were involved in activities against us," he told the Reuters news agency by telephone from an undisclosed location.

"We also warn the political administration of Parachinar to stop siding with the Shia community in all our disputes."

Breakaway faction

Saeed was part of the Tehrik-e-Taliban Pakistan (TTP) but broke away last year after disputes with the umbrella group's leadership.

He is said to have close ties with the Haqqani group, one of the most feared factions of the Afghan Taliban.

The attack in Parachinar came as Mahmoud Ahmadinejad, the president of mainly Shia Iran, was visting Pakistan for a summit to negotiate an end to the war in Afghanistan.

Kurram, the only part of Pakistan's border region that has a significant Shia population, has been plagued by sectarian violence between Sunni and Shia tribes.

The Taliban and al-Qaeda's anti-Shia ideology has meant years of bloody fighting.

Shia Muslims are a minority sect of Islam, arising from a dispute over the successor to the Prophet Muhammad 1,400 years ago.

The TTP, al-Qaeda, and the Afghan Taliban fighting international forces in Afghanistan are entrenched in Pakistan's northwestern tribal areas.

All have been involved in anti-Shia activities for years. They continue to have strongholds in the region despite a series of military operations in the last few years.

Pakistan's army and air force have been conducting operations against armed groups in Kurram since the beginning of the year.

Dozens have been killed in fierce fighting this month.