By Mubasher Bukhari
LAHORE, Pakistan (Reuters) - Pakistan's anti-graft agency arrested the parliamentary leader of the opposition on corruption charges on Monday after a court rejected a plea for bail, a move his party says is linked to planned opposition protests against Prime Minister Imran Khan.
Shehbaz Sharif, a former chief minister of Punjab province and younger brother of former Prime Minister Nawaz Sharif, was arrested outside the Lahore court, his lawyer, Azam Nazir Tarar, said.
The charges are linked to alleged money laundering to buy properties abroad, Tarar said.
"I am disappointed," Tarar told Reuters, adding that the arrest was a reaction to the opposition's threat of nationwide protests calling for Khan to step down.
But Information Minister Shibli Faraz said that courts were free to make their own decisions.
Sharif is one of several opposition leaders facing corruption charges and arrested by the anti-graft body, often before a formal case is registered.
An anti-corruption court in Islamabad on Monday also indicted former President Asif Ali Zardari, husband of assassinated former Prime Minister Benazir Bhutto, for suspected corruption, a prosecution official said. He was arrested in June last year in a separate case and released on bail.
Opposition parties and civil rights groups have long held that the anti-graft agency is used by the military for selected accountability, saying it does not touch powerful generals or Khan's ministers.
Nine major opposition parties last week denounced the military for meddling in politics and rigging the 2018 elections to bring Khan to power.
The military, which has ruled for half of Pakistan's history since its independence from Britain in 1947, denies interfering in politics or election wrongdoing.
"If justice had prevailed, retired general Asim Bajwa would have been arrested," Maryam Nawaz, daughter of former prime minister Sharif, told a news conference after her uncle's arrest.
Bajwa, who oversees the $65 billion China-Pakistan Economic Corridor and is also an adviser to PM Khan, was recently embroiled in controversy following a news report that alleged he had amassed assets worth millions of dollars beyond his means.
He has publicly denied the allegations.
(Writing by Asif Shahzad; Editing by Nick Macfie)