At least 20 people have died in ethnic¹ clashes in the southern Pakistani city of Karachi, officials say.

巴基斯坦官方人员称，至少20人在南部城市卡里奇发生的种族冲突中丧生。

Vehicles and buildings were set on fire

Eyewitnesses² said vehicles had been torched in different parts of the city, which is Pakistan's commercial capital and has a history of ethnic violence.

Karachi is dominated by Urdu-speakers, but there is also a growing population of ethnic Pashtuns.

Officials said the fighting was between members of the two groups, and started after an unidentified man opened fire.

"These are the targeted killings³ by the criminals, drug and land mafias（黑手党，秘密政党） who want to fan ethnic violence in the city," said Faisal Subzwari, a provincial⁴ minister.

Mr Subzwari, a member of the Urdu-speaking Muttahida Qaumi Movement (MQM), said three of those killed were from his party.

The MQM is an ally of Pakistan President Asif Ali Zardari's Pakistan Peoples Party.

Bodies riddled⁵

A spokesman for Mr Zardari said the Pakistani leader condemned⁶ the violence and called for unity⁷.

"The president said that the nation could not afford violence in Karachi at a time when it was already dealing⁸ with the militants⁹ in northern parts of the country," said the spokesman, Farhatullah Barbar.

Doctors in Karachi hospitals said they had received bodies riddled with gunshot wounds.

A spokesman for the Pakistan Rangers¹⁰ paramilitary force said it had arrested 25 suspects and recovered weapons and ammunition¹¹（军火） from them, AFP news agency reported.

Karachi, a city of over 15 million, is the capital of Sindh province.

It contains many Urdu-speaking Muslims descended¹² from people who migrated to Pakistan after the partition of India in 1947.

The Pashtun population has grown further since last year when tens of thousands were displaced by the military operation in the country's north-western tribal¹³ areas.

Some politicians have voiced fears of Taleban infiltration¹⁴ of the Pashtun community.