Islamabad - Unidentified assailants in Pakistan have within the past week killed two journalists and tortured a renowned columnist, while police arrested a reporter-anchor-turned-host of a top YouTube political show amid allegations of a government crackdown on dissent and political opponents.

The attacks began on July 1 when gunmen in Khairpur district in southern Sindh province fatally shot local reporter Ishtiaq Sodharo. The slain man was associated with a local Sindhi-language weekly. His wife accused an area police officer of ordering the deadly attack against her husband. The motive for the killing was not known.

A day later, Iftikhar Ahmed, a reporter for the Urdu-language national Daily Express, was ambushed and killed by unknown gunmen in northwestern Khyber Pakhtunkhwa province while he was on his way to work. Police said an investigation was underway into the motive for Ahmed's killing, including personal enmity.

The International Federation of Journalists (IFJ) on Tuesday condemned the killings, calling on Pakistani authorities to safeguard press freedom in line with their constitutional and international obligations.

"Pakistan's government must take appropriate measures to ensure journalists' safety and security, as required by law, and act to reduce assaults on journalists so that they may carry out their work without fear," the IFJ said in a statement.

On Friday, veteran journalist and political analyst Ayaz Amir was physically assaulted by masked men in the eastern city of Lahore. He was being driven home after his prime-time program on the mainstream Dunya news channel when his car was intercepted.

The 72-year-old nationally known journalist told reporters that the attackers "unleashed blows to my face and dragged me out of the vehicle" on a busy road near his workplace.

Amir alleged the masked assailants also 'tore his clothes" before taking away his and his driver's cellphones.

There were no claims of responsibility for any of the attacks.

Amir was assaulted a day after he delivered a speech at a crowded seminar in the capital, Islamabad, in which he severely criticized Prime Minister Shehbaz Sharif's government and the powerful military's role in national politics.

Former Prime Minister Imran Khan also attended and addressed the seminar, which was organized by a local lawyers' association.

A government statement quoted Sharif as "strongly condemning" the attack on Amir and instructing the authorities in Punjab province, of which Lahore is the capital city, to investigate the incident and bring those responsible to justice.

Separately, the provincial police late on Tuesday arrested prominent TV anchorperson Imran Riaz Khan on the outskirts of Islamabad in connection with a treason case registered against him, his attorney told reporters.

The detained journalist, who has more than 3 million subscribers of his YouTube channel, has been criticizing and highlighting the military's alleged role in Pakistani politics.

The former prime minister denounced Riaz Khan's arrest and tweeted that Pakistan "is descending into fascism."

Imran Khan's nearly 4-year-old coalition government was ousted in a parliamentary no-confidence vote in April, paving the way for then-opposition leader Sharif to replace him and form a new so-called unity government.

The deposed Pakistani leader alleges the United States conspired with his political opponents to remove him from power, charges Washington rejects.

The military denies it is meddling in national politics. The Sharif government also rejects charges it is cracking down on media freedom.

However, Pakistani police in recent days have launched criminal proceedings against several journalists and political talk show hosts known for being critical of both the government and the military.

Pakistan's Electronic Media Regulation Authority (PEMRA), which is responsible for the regulation and issuing of broadcast, print and electronic media licenses, recently also warned digital news outlets and broadcasters against airing content that ridicules state institutions, particularly the judiciary and army. It cautioned that violators could face immediate broadcast suspensions and fines.

Pakistan is identified as one of the most dangerous countries for journalists. Successive civilian governments and military-led security agencies, commonly referred to as the Pakistan establishment, are routinely accused of intimidating and harassing reporters.

But critics note that never have so many media personnel in the country collectively faced criminal proceedings or come under escalating violent attacks within a span of one week.

Pakistan ranks 145 out of 180 countries on the most recent World Press Freedom Index published by Reporters Without Borders (RSF).