A high-level Afghan delegation was due to arrive in Pakistan Monday for talks on peace in the war-torn nation, but analysts warned that without Taliban involvement little would come of the negotiations.
Support from Pakistan, which backed the Taliban regime that held power in Kabul from 1996 to 2001, is seen as crucial to peace in Afghanistan beyond 2014.
Afghan-Pakistani talks were derailed more than a year ago amid a welter of accusations when Rabbani's father Burhanuddin, then head of the peace council, was assassinated by a suicide bomber in Kabul.
This week's talks come as efforts to end the Taliban insurgency in Afghanistan gain a new urgency as the withdrawal of US-led NATO combat troops -- planned for the end of 2014 -- looms ever closer.
But analyst Rahimullah Yusufzai warned no progress of any substance would be made this week, beyond Rabbani getting to meet the Pakistani side for the first time.
"The problem is that the Afghan government has not been in contact with Taliban. Even Rabbani has not been able to get in touch with the Taliban since he became chairman of the council," Yusufzai told AFP.
"How is it possible to achieve results in such a situation when the council has not been in contact with the Taliban?"
Preliminary contacts between the United States and the Taliban in Doha were broken off in March when the militants failed to secure the release of five of their comrades held in Guantanamo Bay.
Yusufzai said that while Pakistan has some influence over the Taliban it was unrealistic to think Islamabad could convince the militants to return to the negotiating table.
Such a move would require "confidence-building measures" from the United States, he said, and in any event could trigger a split in the movement.
Analyst Hasan Askari said that while Kabul and Washington might be keen for some kind of accommodation with parts of the Taliban, the insurgents had little incentive to talk, knowing NATO will leave in two years.
"They are waiting for withdrawal of international troops and are confident that they can make life for Kabul government miserable," he told AFP.