Pakistani authorities say they have detained more than 700 supporters of former Prime Minister Nawaz Sharif as he prepares to return home from exile.
Mr. Sharif, who was ousted by General Pervez Musharraf in 1999, says he will return to the country on Monday.
The Pakistani government has tightened airport security and banned rallies in preparation for the exiled prime minister's return.
Mr. Sharif's party (Pakistan Muslim League - Nawaz) says more than two-thousand people have been arrested.
The return of Mr. Sharif is considered a serious challenge for Mr. Musharraf, who has lost much of his support since trying to dismiss Pakistan's top judge in March.
Mr. Sharif says he intends to fight the rule of President Musharraf, who hopes to win relection by the national and provincial assemblies later this year.
The Saudi royal family and Lebanon's late Prime Minister Rafik Hariri brokered the deal that sent Mr. Sharif into exile in 2000 after he was ousted in a bloodless coup led by General Musharraf.
On Saturday, Saudi Arabia and Lebanese lawmaker Saad Hariri, Rafik's son, urged Mr. Sharif to honor that agreement and abandon his plans to return.
Pakistan's Supreme Court last month said that Mr. Sharif has the right to return to the country.
Both Mr. Sharif and his younger brother, Shahbaz Sharif, are in danger of arrest if they return from exile.