ISLAMABAD - Anti-corruption authorities in Pakistan have arrested the owner and editor-in-chief of the country's largest private media group for his alleged wrongdoing in a 34-year-old case related to a real estate purchase.

The National Accountability Bureau (NAB) said in a statement on Thursday it took Mir Shakilur Rehman into custody in the eastern city of Lahore for failing to answer questions during an investigation into the matter.

The arrest comes as media outlets and journalists in Pakistan say they have come under increased pressure in recent years from state institutions and security agencies, charges officials reject.

Rehman's Jang Media Group owns Pakistan's largest Urdu-language GEO News channel and several prominent newspapers, including the mainstream English daily - The News International.

The media group, which has been critical of the government, denounced Rehman's arrest as a "political victimization and an attack on the freedom of expression." It noted in a statement the property in question "was bought from a private party 34 years ago and all evidence of this was given to NAB."

Rehman's arrest drew strong condemnation from local and international advocates for free media. Opposition political parties also denounced the arrest as an action allegedly orchestrated at the behest of Prime Minister Imran Khan to deflect attention from public criticism of his nearly two-year-old government's economic and anti-corruption policies.

Khan's aides rejected the accusations, telling critics the NAB has been operating in Pakistan as an autonomous institution for nearly two decades.

The U.S.-based Committee to Protect Journalists, or CPJ, demanded the NAB immediately release Rehman and drop what it said was a drummed-up case against him.

"This arrest over a 34-year-old land deal makes a mockery of Pakistan's claim to be a democracy that upholds freedom of the press," said Steven Butler, CPJ's Asia program coordinator.

The independent Human Rights Commission of Pakistan (HRCP) said it was "deeply concerned" at Rehman's arrest, saying the government should immediately take steps to address the issue and prove its commitment to press freedom.

"The journalist community sees this as yet another attempt to gag a beleaguered independent press," the HRCP said in a statement.

Critics say in addition to pressure from state institutions, powerful private entities and loyalists of major political parties also have physically assaulted and even murdered journalists in certain cases to silence critical voices.

The latest incident happened just weeks ago when a local television reporter, Aziz Memon, disappeared in southern Sindh province while on his way to work. Police later found his body dumped in a puddle, with signs of torture.

Memon had complained in messages he circulated on social media that he was being threatened by unknown men and even by area police for his critical reporting of the Pakistan Peoples Party, which is currently ruling Sindh. An initial investigation suggested Memon was strangled. Media freedom watchdog groups have called on the government to bring his killers to justice.