Nawaz Sharif and his daughter Maryam Nawaz have been held at a high-security prison in Rawalpindi since July 13 following their conviction on corruption charges.
Taha Siddiqui, who won France's highest journalism award the Albert Londres prize in 2014, said he was attacked by up to a dozen men en route to the airport in Rawalpindi.
Pakistan's capital was tense Sunday after attempts to disperse anti-blasphemy protests by Islamists ended in deadly violence, as the military appeared hesitant to respond to a government call for help.
Hundreds of supporters of the Tehreek-e-Labaik Pakistan party have been blocking the route into Islamabad for nearly 10 days, demanding the minister of law be sacked.
The roughly 2,000 protesters are demanding the resignation of the federal law minister over a hastily-abandoned amendment to the country's blasphemy laws.
The former premier, who was forced out by the Supreme Court in July over a scandal kindled by the Panama Papers leak, had been facing an arrest warrant for failing to appear at hearings since early October.
Pakistani Finance Minister Ishaq Dar did not speak to the media after his appearance in court in Islamabad but has dismissed all the allegations against him.
Pakistan's military brushed off speculation on Monday that a new US strategy for neighbouring Afghanistan could include taking a stronger line against Islamabad, insisting the country has done all it can to tackle militancy.
Prime Minister Nawaz Sharif on Saturday said a new airport in Pakistan's capital will be operational by mid-August, replacing the cramped Benazir Bhutto International Airport ...