Authorities in Pakistan have rounded up opposition supporters and deployed thousands of police and paramilitary troops in Karachi, ahead of a planned rally led by the country's suspended top justice.

Opposition leaders say hundreds of activists were detained during pre-dawn raids in Karachi. Hundreds have gathered in the coastal city to show support for Chief Justice Iftikhar Chaudhry. He was pulled from the bench by Pakistani President Pervez Musharraf in March for alleged abuse of office.

Pro-Musharraf parties are planning to hold rival demonstrations at the same time in Karachi Saturday.

The government's suspension of Chaudhry has outraged the judiciary and the opposition, who have held a series of protests across the country. The controversy has become the most serious challenge to General Musharraf's authority since he seized power in 1999.

Last week, thousands of people turned out to greet Chaudhry at a rally in the eastern city of Lahore.

Chaudhry denies wrongdoing and he says his suspension was unconstitutional. He has also challenged the panel of judges reviewing his case, calling them biased. A separate inquiry into his allegations began this week.

Some information for this report was provided by AFP and Reuters.