17 January 2013 Last updated at 10:42 ET

Pakistan politician Manzar Imam shot dead in Karachi

No group has said it carried out the attack on Mr Imam

A provincial lawmaker has been shot dead in the Pakistani city of Karachi, in what police say appears to be a sectarian attack.

Manzar Imam was a Shia Muslim member of the Sindh provincial assembly for the Muttahida Quami Movement (MQM).

Two police guards and a personal security guard were also killed when four men on motorbikes opened fire on his vehicle on Thursday.

Protests erupted and sporadic gunfire was heard as news of the attack spread.

Businesses shut early because of the unrest and the authorities say that markets in the city will remain closed on Friday.

No group has said it carried out the killing.

In August 2010 another Shia MQM parliamentarian, Raza Haider, was shot dead by the Lashkar-e-Jhangvi militant group.

Mr Imam's killing comes just a week the same militant group bombed a snooker hall in a mainly Shia area of the city of Quetta in neighbouring Balochistan province.