ISLAMABAD, Pakistan (CNN) -- Shortly after making their coalition official, Pakistan's main opposition parties on Sunday called on President Pervez Musharraf to immediately convene parliament.
Asif Ali Zardari, widower of Benazir Bhutto, shakes hands with Pakistani former premier Nawaz Sharif.
The leaders of both parties vowed to restore Pakistan's deposed judges within 30 days after the first session of parliament. Musharraf said Saturday that he would call parliament into session within two weeks.
Musharraf sacked nearly all of the country's Supreme Court justices and many other judges across the country shortly after declaring a state of emergency in early November. The emergency order was lifted six weeks later, but none of the justices were reinstated.
Former Chief Justice Iftikhar Chaudhry and several other of the sacked justices remain under house arrest. Their supporters say they were ousted because they were set to rule against the legitimacy of Musharraf's third term in office. Chaudhry was first suspended by Musharraf on March 9 and protesters gathered outside his official residence in Islamabad on Sunday to mark the one-year anniversary.
Asif Ali Zardari, head of the Pakistan People's Party, and Nawaz Sharif, head of the Pakistan Muslim League-N, spoke Sunday at a news conference outside Islamabad shortly after signing an agreement to make their parties' coalition official. Watch Zardari address the need for cooperation »
They have not named a nominee for the prime minister post, saying that announcement will happen when parliament is called into session.
PPP, the party of slain opposition leader Benazir Bhutto, and PML-N won the majority of seats in Pakistan's February 18 parliamentary election
When asked about working with Musharraf's government, Zardari -- Bhutto's widower -- said the coalition believes the new prime minister will be able to work with the office of the presidency in harmony.
Police in Islamabad were on high alert for demonstrations on Sunday, firing tear gas at one point.
Chaudhry's suspension triggered massive, widespread protests that weakened Musharraf's grip on power and forced him to reinstate the chief justice.
Protesters gather every week in front of the justices' official residences, and the demonstrations are usually marked by tear gas -- except when high-profile political leaders are present.
The demonstrations are also marked by unusual symbols; a few protesters sported boxing gloves on Sunday.
"I'm wearing this glove, showing that last punch always by the people of Pakistan," said female attorney Tasleem Abbasi.
"This is a legal punch on the faces of dictators." E-mail to a friend
CNN Correspondent Reza Sayah and Producer Zein Basravi contributed to this report