KARACHI: Bodies are piling up in Pakistan's largest city as it suffers one of its most violent years in history, and concern is growing that the chaos is giving greater cover for the Taliban to operate and undermining the country's economic epicenter.   

Karachi, a sprawling port city on the Arabian Sea, has long been beset by religious, sectarian and ethnic strife. Here armed wings of political parties battle for control of the city, Sunnis and Shias die in tit-for-tat sectarian killings, and Taliban gunmen attack banks and kill police officers. With an election due next year, the violence could easily worsen.

According to the Citizens' Police Liaison Committee, a civic organisation that works with police to fight crime, the violence has claimed 1,938 lives as of late November, the deadliest year since 1994, when the CPLC began collecting figures. Police tallies put the dead at 1,897 through mid-October.

The Taliban seem to be taking advantage of the chaos to expand their presence in the city, a safe distance from areas of Pakistani army operations and US drone strikes.

During recent Supreme Court hearings, judges ordered authorities to investigate reports that as many as 8,000 Taliban members were in the city.

Security officials say the Taliban raise money in Karachi through bank and ATM robberies, kidnappings and extortion, and are recruiting as well. The head of the city's Central Investigation Department, Chaudhry Aslam, who is tasked with tracking down militants, said the Taliban have killed at least 24 of his officers this year.

Regular citizens are often caught in the middle. Samina Waseem says her son Aatir, 21, went out on May 22 to get his phone fixed. Three days later she found his body in the morgue with a gunshot wound through his head.

She's convinced he was killed because he belonged to the Mohajir community, descended from people who moved from India to newly created Pakistan when the subcontinent was partitioned in 1947.

Part of Karachi's problem is that since 1947 its population has mushroomed from 435,000 to 18 million. The metropolis ranges from the high-end neighborhoods of Clifton where people live behind bougainvillea-covered walls and eat arugula and fig salads at posh restaurants, to concrete block houses on the dusty outskirts. There migrants move in from the rugged northwest where the US is waging its war with the Taliban, and from the flood-prone plains of Sindh.

That population growth is marked by spurts of violence. Currently the overarching struggle appears to be between two powerful forces. One is the Muttahida Quami Movement (MQM), the city's dominant force, which represents Urdu-speaking Mohajirs. The other is the Awami National Party (ANP). It represents Pashtuns whose numbers are increasing as their ethnic kin flee the northwest.

The MQM prides itself on being the protector of middle-class, liberal, secular values in a country where extremism and religious conservatism hold sway. It says the Taliban began moving into Karachi in force, driven south by a military offensive in 2009, and is wreaking havoc while hiding among the Pashtun. ''We are trying our level best to keep Karachi alive,'' said Engr Nasir Jamal, of the MQM.

The ANP and the Pashtuns believe the MQM is nervous that Pashtun population growth will undermine their hold on Karachi, and that it is targeting Pashtuns to intimidate them. The Pashtuns acknowledge that the Taliban are a big problem, including for them, because the terror group has also been killing its members. But they say the MQM exaggerates the problem.

The battle lines are visible across the city. MQM flags and posters blanket the Urdu-speaking neighborhoods, and red flags and graffiti mark ANP territory in the poorer, blue-collar neighborhoods.

Theirs is hardly the only conflict. The Pakistan People’s Party (PPP), which heads the national government, says 450 of its activists have been killed over the last 4 years. Nationalists from Balochistan province find refuge in the city, Sunni extremists target Shias they consider infidels and the Shias fight back. Add waves of people displaced by floods over the last three years, and the lack of land and resources becomes a toxic brew. ''This is a war for controlling Karachi,'' said Taj Haider, a leading member of the PPP in Sindh.

During pitched battles between armed wings of political parties last year, whole neighborhoods were cut off, children kept away from school and residents shot and killed while shopping for food. This year the violence has been more spread out.

The effect on Karachi's business community is being felt, said Mohammed Atiq Mir, chairman of the All Karachi Trade Association. He estimated that 20,000-25,000 businesses have left, and that the economic loss equals about $10 million dollars a day. Businessmen he talks with have begun hiring private security guards and are getting licenses to carry weapons.

The city's police are often outnumbered and outgunned. There is one police officer for every 600 people, compared with 1 to 150 on average in neighboring India, said Sharfuddin Memon, an adviser to the Sindh provincial government. There is no witness protection program, so people are reluctant to testify. De-weaponization plans have gone nowhere.

Meanwhile the deaths multiply, and the death of Samina Waseem's son remains one among hundreds that go unexplained and unpunished.

“I just want that whoever did it to just tell us, why he did it,” she pleaded. “Just tell a mother why he killed my son.”