Police have arrested 185 people ahead of the formal start of a government-ordered targeted operation aimed at cracking down on those involved in violence in the southern Pakistani city of Karachi.

Those arrested include 16 illegal immigrants and 43 absconders, police said on Thursday.

The arrests came ahead of a planned operation by paramilitary forces to drive out criminals from certain areas of Pakistan's largest city, located on the coast of the Arabian Sea.

The operation was discussed at a special session of the Federal Cabinet after extensive consultation for two days by Prime Minister Nawaz Sharif with stakeholders, including Sindh Governor Dr Ishratul Ibad, Chief Minister Syed Qaim Ali Shah, leaders of various political parties, representatives of business community and media personnel.

The paramilitary Rangers force is to be given full legla and investigative powers to carry out the operation, Chaudhry Nisar Ali Khan, the country's interior minister, announced on Wednesday.

A Rangers official told Al Jazeera on Thursday that those powers had not yet been granted, but that once they were, the force would begin a full-scale operation against those involved in the violence.

Navy captain shot

Meanwhile, a senior Pakistan navy officer was shot dead and his Swedish wife wounded in Karachi on Wednesday, police said.

The couple were shot on a busy thoroughfare near the National Stadium, a cricket venue, in the city's eastern district.

"Two gunmen riding a motorbike intercepted Captain Naveed's vehicle and opened fire, killing him on the spot," local police official Tahir Naveed told AFP.

He had only one name for the dead officer.

Naveed's wife sustained a bullet injury in the attack and has been taken to a naval hospital, he added. 

Karachi is suffering from an unprecedented wave of killings and kidnappings blamed on Islamist fighters, criminals, and ethnic and political tensions.

Gang wars fed by ethnic and political bitterness, drugs and the Taliban, have created a culture of impunity in the city of 18 million, and the past two years have seen record death tolls.

In the first six months of 2013, 1,726 people were killed compared with a previous high of 1,215 in the same period last year, according to the Human Rights Commission of Pakistan.

Source: Al Jazeera and agencies