Police were given orders to "shoot on sight" on July 9 in efforts to quell the violence [AFP]

At least 20 people have been killed and dozens more injured in continued violence between rival groups in Pakistan's largest city, police and officials said.

The recent spate of pitched battles in the eastern neighbourhoods of Karachi, the commercial hub of the country, killed 12 people on Friday and eight more on Saturday, according to police sources.

The violence is said to be a result of clashes between armed activists of Karachi's most powerful political party, the Muttahida Qaumi Movement (MQM), and its breakaway faction, the Mohajir Qaumi Movement-Haqiqi (MQM-H).

Saud Mirza, a police official in Karachi, said on Friday that the violence erupted when "some men of a group entered Khokhrapar area of Malir and targeted their opponents".

Late on Saturday, hundreds of people, including officials and supporters of MQM attended the funeral of two of the victims.

"The unarmed innocent people were brutally killed in their houses and on the streets in the morning at around
7:30am," Mustafa Kamal, an MQM official told reporters.

He said most of the victims were either workers or supporters of MQM, but did not speculate on who the killers were.

Escalating violence

The violence in Karachi has escalated since earlier this month,  and has taken the lives of more than 150 people.

Police, in their attempts to return order to the city, declared a "shoot on sight" policy on July 9 after at least 98 people were killed in street violence over a span of three days.

"We have issued orders to the security forces to shoot anyone involved in violence on the spot," Sharjeel Memon, the provincial information minister, told the Reuters news agency on Friday.

"In addition to the police and Rangers, another 1,000 personnel of the Frontier Constabulary will be deployed in the city to control the violence," he said.

Karachi, home to more than 18 million people, has a long history of ethnic, religious and sectarian violence.

A recent report from the Human Rights Commission of Pakistan said 1,138 people were killed in Karachi in the first six months of 2011, of whom 490 were victims of political, ethnic and sectarian violence.

According to officials, Karachi contributes 68 per cent of the government's total revenue and 25 per cent of country's GDP.