KARACHI: Pakistan's financial hub Karachi saw its deadliest year in two decades in 2012, with around 2,000 people killed in violence linked to ethnic and political tensions, raising fears for elections due this year.

Karachi, a business centre with a population of 18 million, is the beating heart of the nuclear-armed country of 180 million.

It accounts for 20 per cent of GDP, 57 per cent of tax revenue and elects 33 lawmakers to the federal parliament.

Yet enormous waves of migration have tightened resources and exacerbated a fight for identity and control that has only become deadlier in the five years since the main ruling Pakistan People's Party (PPP) took office in Islamabad.

Trapped in the middle are ordinary people who one day leaves home, never to return alive — victims of faceless gangs condemned by political parties yet linked to ethnic and political factions, and who escape with impunity.

“My son went to pay his respects at his father's grave, but he never came back. We found his mutilated body in a bag,” says Shahida, sobbing uncontrollably in her damp home.

Faysal, 16, was her only son. When he went missing last month from their home and was later found in a rubbish-strewn alley in the working class district of Lyari, her world collapsed.

He was shot in the head, and there were drill marks on his head and stomach, says Faysal's uncle Mohammed Hussein.

“We don't know who did it and why... I don't have a reason to live any more,” his mother cried.

According to the Citizens-Police Liaison Committee, 2,124 people were killed in Karachi in 2012, the worst year since records began nearly 20 years ago.

The Human Rights Commission of Pakistan (HRCP) says 1,800 people died in targeted killings in the first nine months of 2012. In 2011, it put the number at 1,000, which was then the deadliest in 16 years.

Karachi has all the ingredients of an explosive cocktail — gang warfare, land grabbings, drugs, extremism, political rivalries, ethnic tensions, poverty and a mushrooming population owing to migration.

Police insist killings related to ethnic and sectarian disputes accounted for only 20 per cent of the murders, but rights activists say a shortage of law enforcement officers is part of the problem.

“Karachi is becoming a city where controlling violence is becoming increasingly difficult because of an insufficient police force, which is less than 30,000 for around 18 million people,” says Zohra Yusuf, HRCP chairwoman.

Pakistan is scheduled to hold elections by the end of May, which will mark the first democratically elected transition of power ever in the country, dominated for decades by military rulers.

No date has yet been set for the polls, but parties are disputing the boundaries of constituencies and accuse each other of distorting their respective voter list to inflate their chances of success.

“I am very fearful about the coming elections," said Fateh Muhammad Burfat, a criminologist at Karachi University. The different groups “will try to show their power and there is only one way to show power here — it is violence.”

When British colonial rule ended in 1947, and Pakistan was created, Karachi became a capital overnight and the destination of ten thousands of Indian Muslims.

Today, the Muttahida Qaumi Movement (MQM) controls most of the city apart from Lyari, a bastion of support for the PPP, and areas home to new migrants, ethnic Pashtuns from the northwest.

For the past three or four years, Lyari has seen clashes blamed on two rival groups.

“Land in Karachi is very precious and grabbing is the bone of contention, the mother of all conflicts,” says Zafar Baloch, number two in the first group.

In the spring, a police operation tried but failed to dislodge his men from Lyari.

“Sometimes they call us drug mafia, sometimes they call us land mafia, sometimes gangsters, they give different allegations because we are their main obstacle to the project to control Lyari,” he told AFP.

Outside Lyari, ethnic tensions are blamed for much of the violence.

The MQM vents about alleged Talibanisation, pointing to suicide and bomb attacks linked to the Taliban-led insurgency.

“The major criminals are these suicide bombers, these Taliban extremists, whoever they are, are here and have access to local criminals,” complains Khawaja Izhar ul-Hasan, a provincial cabinet minister from MQM.

“Now they are like a mafia, from mobile phone snatching on the street to bank robbery, everybody is connected.”

The Awami National Party (ANP) accuses the MQM of power politics.

"MQM wants to occupy and control the whole city," said Bashir Jan, ANP secretary general for southern province Sindh, of which Karachi is the capital, who says he has survived three assassination attempts since 2007.