KARACHI (AFP) - A bomb targeting a passenger train in southern Pakistan killed at least seven people and wounded more than 30 on Sunday, officials said, the latest in a series of attacks this year.

The bomb went off near Unar station, 450km northwest of Karachi, and badly damaged several carriages.

"The death toll in the explosion rose to seven after two injured persons died of their wounds in a hospital in Jacobabad town," a senior local administration official, Sardar Jamali, told AFP.

He said the Khushhal Khan Khattak express was travelling to Peshawar from Karachi when it was hit by the blast, which injured more than 30 people and damaged hundreds of metres of track.

Pakistan has endured a bloody start to the year with 114 people killed in attacks in January, according to an AFP tally.

On Jan 29 Prime Minister Nawaz Sharif announced talks with the Pakistani Taleban to "give peace another chance", but some 60 more people have died in Islamist-linked violence since then.

Three carriages were derailed on Sunday and two of them were severely damaged by the force of the explosion.

A senior railways official Sikandar Lashari confirmed the toll of the bombing, for which there has been no claim of responsibility.

Jamali said the bomb was likely an improvised explosive device. The general manager of Pakistan Railways, Anjum Parvaiz, suggested it was a remote-controlled device planted on the track.

Parvaiz said 800m of track had been damaged.

A bomb in one of the compartments of a train on the same route last month killed three people and wounded 20 in the central town of Rajanpur in Punjab province.

Pakistan since July 2007 has been gripped by a local Taleban-led insurgency concentrated largely in the northwest.

The government says more than 40,000 people have been killed in violence since 2001, when Pakistan allied itself with the US-led "war on terror".