"We have been informed by the prime minister that in his speech he will announce the restoration of chief justice Chaudhry," Chaudhry Nisar, an opposition member of parliament, said.
The reports came as Nawaz Sharif, the leader of Pakistan's main opposition Pakistan Muslim League-Nawaz (PML-N) party, led a convoy towards the capital Islamabad where opposition supporters and lawyers were planning to hold mass demonstrations to press for the restoration of sacked judges.
Chaudhry, the former supreme court justice, was dismissed by Pervez Musharraf, the former president, on November 3, 2007 along with 60 other judges, 53 of whom have since been reinstated.
However, Asif Ali Zardari, Musharraf's successor, has repeatedly reneged on promises to return Chaudhry to his post with analysts suggesting that he feared the chief justice could pose a threat to his position.
Opposition claims win
Senior members of Sharif's PML-N painted the prospective announcement as a win for the opposition.
Al Jazeera's Imran Khan, reporting from Lahore, said that the official announcement was still to be made but it seemed that officials had decided that this was the only course open to them.
"Many supporters of the deposed chief justice are treating this as fact, there are flags being waved outside his residence and supporters are gathering. There is a real celebratory atmosphere," he said.
"This is going to be seen one of two ways: Either a blow to the government and an embarrassing climb down or it is going to be seen as a strike for national political unity depending on who you speak to."
Unnamed officials also told news agencies that "a constitutional package" would be announced along with the reinstatement of the chief justice.
March to Islamabad
It was not immediately known whether Sharif would continue to lead his convoy of about 200 buses, cars, lorries and motorcycles to Islamabad where opposition supporters and lawyers were planning a mass sit-in outside parliament.
"Our destiny is Islamabad. We have left for Islamabad," Sharif told Pakistan's Geo television in a telephone interview as he set off from the eastern city of Lahore.
"The response from the people is amazing. It is a golden moment in Pakistan's history. It is a prelude to a revolution."
Political tensions have risen in Pakistan in recent weeks, with Zardari coming under mounting pressure since the supreme court banned Sharif and his brother, Shahbaz, from holding elected office.
The government had vowed on Saturday to review last month's supreme court ruling, but PML-N officials had dismissed that announcement and said that their "long march" would continue.
Tariq Azeem Khan, a senator from the Pakistan Muslim League-Quaid party, explained that "Zardari finds himself in a very difficult position".
"His ratings are at an all time low, so I think having seen the public anger ... he will probably have to come to some sort of agreement with Nawaz Sharif," Khan said.