KARACHI: From his home off a dirt road cluttered with trash in Pakistan's teeming city of Karachi, policeman Didar Ahmed's son shows the bloodstained jacket his father was wearing when gunmen cut him and three colleagues down in a hail of bullets last month.

Ahmed's brother Gulzar looks at the bullet-riddled garment with a blank stare.

He recalled how days before his brother's death, they had talked about the rising dangers of police work as officers increasingly come under attack by criminal gangs and militants from the Pakistani Taliban.

''He was sitting here and told me: 'The situation in the city is deteriorating so if something happens to me, you take care of my kids and family,''' Gulzar said.

Ahmed was one of 44 police officers killed during the first two months of the year in Pakistan's largest city, a particularly violent start to the year for the police.

The force was already reeling from 166 officers killed last year, roughly one every other day and a four-fold increase from just five years earlier.

Being a police officer has never been especially easy in this sprawling metropolis on the southern coast, where the population has surged from roughly 10 million in 1998 to some 18 to 21 million today, so much that an exact count has proven elusive to authorities.

But recent figures suggest the profession has become even more perilous, in large part because the Pakistani Taliban and affiliated militant groups have gained a foothold here, police and analysts say.

Police Chief Shahid Hayat says they are responsible for roughly 60 per cent of the recent police killings. Much of the focus on militancy in Pakistan since 9/11 terror attacks in the United States has been on the vast northwest tribal regions bordering Afghanistan, where the army is fighting militants.

But as fighters increasingly move into settled areas of the country such as Khyber Paktunkhwa province in the north, and Karachi in the south, it has put immense strain on law enforcement agencies that are generally less well-funded and trained than the army.

''It's a big concern,'' said Hayat of the killings. He was brought in last September to oversee a new campaign to bring down the violence plaguing the city.

Karachi's problems are extensive: extortion, kidnapping-for-ransom, targeted assassinations, and car theft, to name a few.

Newly-elected Prime Minister Nawaz Sharif, acutely aware of the city's importance to the country's economy ordered paramilitary Rangers and police to bring order to it.

Police have been killed on their way to and from work. Ahmed's family said he would put on his uniform at the station house so people wouldn't know his profession.

Grenades have been lobbed at police stations and vehicles. In two of the most shocking attacks, the man dubbed the city's ''toughest cop,'' Chaudhry Aslam, was killed in a bombing claimed by the Pakistani Taliban

in January, followed by a roadside bomb that killed 13 police officers in February. To be sure, the Pakistani Taliban are not the only driver of the violence in the city.

Karachi has been a cauldron of ethnic and political tension for decades, where political parties have militant wings, gangs make money through drug-trafficking, land grabbing and other forms of crime, and sectarian groups target the city's Shia Muslim minority.

Just Wednesday, at least 15 people were killed in a gangland shootout, and six police were wounded.

Samina Ahmed from the International Crisis Group said it's not necessarily that the jihadi threat has grown, but that state control has increasingly withered in Karachi and other cities, allowing criminality and militancy to thrive.

''Large parts of Karachi can't be policed effectively because the police don't have the means, either the bodies or the technology,'' she said. ''It's a megacity and megacities require efficient law enforcement and that is what Karachi lacks. So is it that the jihadi threat that can't be tackled or is it that the state isn't trying to tackle it seriously enough?''

Religious militants have long had a presence in the city, but it was generally used by them as a place to seek medical treatment, raise money through bank robberies or to recruit at the city's massive network of religious schools.

But the combination of Pakistani military operations in the northwest starting in 2009, along with American drone strikes, drove many militants to seek shelter here among the city's large Pashtun population.

Raja Umar Khattab, an investigator with the police unit responsible for hunting down militants, knows the dangers of the job, his neck scarred from a roadside bomb that almost killed him.

When the violence in Karachi began to rise, he said, militants first attacked politicians and activists from the Awami National Party, which has a strong presence in Pashtun areas.

Dozens of ANP members were killed, and militants tore down flags from their offices. Then they turned their attention on law enforcement personnel, he said.

"They are targeting police to bring down the morale of the police and to terrorise the police, and therefore they come on motorcycles in Karachi and run away after attacking two or three policemen," he said.

The police are frank about the challenges they face.

Hayat said he has roughly 27,000 police officers and generally about 9,000 are on protection duty for "VIP" individuals, like judges or businessmen or politicians.

Some 3,000 to 4,000 officers will be in the field at any given time, yet only 1,500 have bulletproof vests.

Station houses are often dilapidated and uninviting to citizens, who often view police with suspicion. Rights groups and analysts say police are sometimes complicit with criminal gangs and sometimes use excessive force.

Officers are quickly transferred, lessening the time they have to learn the job or the community.

The paramilitary Rangers have been based in the city since the mid-nineties and have been an active part of the recent anti-violence campaign.

While they're generally better-equipped and trained, critics say their presence has allowed the government to avoid investing the time and energy into improving the police force.

Many in the police say the operation so far has been a success because murders and extortion complaints have fallen.

They said the police killings are an attempt to demoralise law enforcement. Khattab said there are now no more so-called "no-go areas" that police cannot enter.

Hayat said the police are reinforcing stations in the most dangerous areas and have directed officers to only travel in two vehicle-convoys so they have more manpower to fight back.

"They should at least have it in their mind that we're going to hit back, and we're going to kill them," he said.

Others are not so sure.

Amanullah Mehsood, a senior ANP politician in Karachi, said he can't even visit his wife and children in their Pashtun neighborhood of the city because the militants have threatened to kill him.

He said few people in the Pashtun areas of the city trust the police or Rangers so they don't pass along tips.

"The police come in an area and the TTP ... leave," he said, referring to the Pakistani Taliban's by its official name, Tehreek-e-Taliban. "Then the Rangers and police leave and the TTP is back."