Political sources told Reuters news agency that the two leaders were negotiating on behalf of other leaders within their groups and sounded upbeat in their assessment of the talks.
"There is a common will to reach a result. I think we are heading for a solution," one source close to Berri said.Opposition campaign
Berri, who leads the Amal Movement, Christian leader Michel Aoun and the Shia Hezbollah movement, have been engaged in a campaign to topple the government of Fuad Siniora, the prime minister, after he refused to accede to their demands for a unity government which would have given them a greater share of power.
Five Shia ministers and one Christian ally resigned from the cabinet to protest at Siniora's refusal to meet their demands.
Before the meeting, al-Hariri, who had just returned from Saudi Arabia, announced that he was seeking a solution for the crisis that has gone on for too long.
"We should get out of it in a way that there is no victor and no vanquished," he said, adding that neither the majority nor the opposition can run the country on its own.
The opposition has staged protests and sit-ins in central Beirut - just outside the prime minister's office - since December 1.
In January, the situation turned violent with eight people killed in clashes between the two sides.Breakthrough sought
"This meeting, in my opinion, is part of efforts that could be continued in the coming hours and days until we reach breakthroughs that people are waiting for," Ammar Houri, a member of al-Hariri's parliamentary bloc, told Voice of Lebanon radio on Friday.
Trad Hamadeh, the Hezbollah labour minister who resigned in December, told the station that "there must be a Lebanese solution" before the Arab League summit scheduled for March 28-29 in Saudi Arabia.