Asif Ali Zardari has accused Imran Khan of being the military's "blue-eyed boy" (File Photo)

Pakistan's largest private broadcaster abruptly took an interview with former president Asif Ali Zardari off air shortly after it began, deepening fears of increasing censorship in a country already among the most dangerous in the world for media.

Geo News did not give a reason for why it cut the interview -- mere minutes after it started -- with Zardari, who is also the widower of assassinated former prime minister Benazir Bhutto.

There have been accusations in recent years of the country's powerful military putting pressure on the media to stop coverage critical of its policies -- allegations it denies.

Zardari and his Pakistan Peoples Party (PPP) have a tense relationship with the military, and he is currently facing corruption charges as part of a wider crackdown.

Hamid Mir, the interviewer, complained on Twitter about increasing censorship in Pakistan after the show was taken off the air Tuesday night.

"Those who stopped it (the interview) have no courage to accept publically that they stopped it," he tweeted.

He apologised to viewers, adding: "it's easy to understand who stopped it? We are not living in a free country."

Mir made international headlines in 2014 after surviving multiple gunshot wounds in an attack he blamed on the shadowy Inter Services Intelligence agency (ISI), Pakistan's top spy organisation.

Criticism of the country's powerful security establishment has long been seen as a red line for the media, with journalists and bloggers complaining of intimidation tactics including kidnappings, beatings, and even killings if they cross that line.

Last year, the Committee to Protect Journalists (CPJ) said in a report that the military has "quietly, but effectively, set restrictions on reporting".

Geo News has faced pressure from authorities in the past. Last year, it was temporarily taken off the air in the run-up to the general election won by Imran Khan.

Some of Pakistan's biggest and most powerful media outlets have claimed they were pressured to tilt their coverage towards Khan during the campaign, an accusation the military denied.

Zardari has accused Prime Minister Khan of being the military's "blue-eyed boy".

After his wife's assassination, Zardari served as president from 2008 until 2013, and has long been the subject of corruption allegations. He is widely known in Pakistan as "Mr Ten Percent".

He was arrested last month in connection with a high-profile money laundering case that saw millions allegedly siphoned out of the country, allegations he has denied.