Karachi: Pakistan on Thursday ordered hundreds of extra paramilitary policemen onto streets of the country's biggest city after a fresh night of political and ethnic violence killed 14 people.

"We have dispatched 500 FC (Frontier Constabulary) troops in Karachi," Interior Minister Rehman Malik told reporters in Islamabad.

The move comes five days after Malik claimed that the government had restored order to parts of Karachi, where a week of unrest killed 95 people in the deadliest year of violence in Pakistan's financial capital since 1995.

The overnight violence erupted after provincial minister Zulfiqar Mirza, from the main ruling Pakistan People's Party, criticised its former coalition partner, the Muttahida Qaumi Movement (MQM) and its exiled leader Altaf Hussain.

The MQM last month quit the PPP-led coalitions that govern the country and the southern province of Sindh, of which Karachi is the capital.

The party, which represents the Urdu-speaking majority in Karachi, has called for nationwide protests over Mirza's criticism.

Roads were deserted Thuesday with minimal traffic in normally bustling commercial and residential areas of Karachi, where most shopping malls, markets and restaurants were closed.

"At least 12 people, including a paramilitary Rangers soldier, were killed overnight," city police chief Saud Mirza told AFP.

He said 21 people were injured and that more than a dozen vehicles had been set ablaze in different parts of the city, adding that police had rounded up around 160 suspects.

Political and ethnic violence in Karachi is blamed on loyalists of MQM and those of the Awami National Party (ANP), which still belongs to the ruling coalitions and which represents migrant Pashtuns from the northwest.

The worst affected areas are impoverished and heavily populated neighbourhoods where most of the criminal gangs are believed to be hiding.

The Human Rights Commission of Pakistan says 490 people were killed in targeted killings in Karachi in the first half of the year, compared to 748 in 2010 and the worst since 1995.