The party of former Prime Minister Nawaz Sharif has alleged that the authorities are detaining hundreds of supporters ahead of the ousted leader's return to Pakistan this week.
The Pakistan Muslim League-Nawaz (PML-N) said the arrest of hundreds of party members across the country was an attempt to prevent it from staging a welcome-home rally upon Sharif's return from London on July 13.
Mushahid Hussain Syed, a senator and head of the PML-N's media committee, told RFE/RL on July 12 that a "huge crackdown" had been launched against the party.
Syed claimed that 220 party members were arrested in the city of Rawalpindi and hundreds in the eastern province of Punjab, Sharif's home province, including 150 in the provincial capital, Lahore.
Pakistani police have said about 100 people were detained "to avoid violence."
Syed said party members and supporters were not preparing to stage a protest, but only to welcome their ousted leader.
PML-N leaders have accused Pakistan's powerful military, which has an oversized role in domestic and foreign affairs, of attempting to destabilize the party ahead of general elections scheduled for July 25.
Sharif, ousted by the Supreme Court for corruption in July 2017, was convicted last week and sentenced to 10 years in prison over purchases of luxury apartments in London.
His daughter, Maryam Nawaz, was sentenced to seven years in a case stemming from the 2016 Panama Papers leaks.
Both were sentenced in absentia while in Britain, where Sharif's critically-ill wife is in hospital.
Sharif has not yet appealed his conviction and is expected to be taken into custody as soon as he lands in Lahore.
His brother, Shahbaz Sharif, who now heads the PML-N, condemned the arrests and demanded that everyone detained be immediately released.
Authorities in Lahore set up shipping containers and other barricades to block roads leading to the airport to prevent Sharif's supporters from gathering there.
In a televised appeal to supporters from London on July 11, Sharif said he was not afraid of prison and asked people to vote for his party in the July 25 vote.
Sharif also again criticized the military, saying Pakistan now hasd a "state above [a] state."
With reporting by AP and Reuters
