Military negotiator Lieutenant Filipo Tarakinikini told the Herald that the release would take place before the chiefs met.
"What we did in today's talks was break the walls down and tell them we were not trying to threaten them, that we wanted to settle this peacefully."
He said the military had confirmed that a group from the Taukei nationalist movement was the driving force behind Speight.
"Once this group came into negotiations, we sat them before the commodore [armed forces commander Frank Bainimarama] and they could both talk because they both had the mandate."
A Speight negotiator, Iliesa Buvuloco, described the deal as very positive.
He believed Speight would inevitably end up in Government. "Of course - he is our leader."
Last night's three-hour talks came after Speight left the parliamentary compound - for just the second time - and was taken by the military to its headquarters.
While he was there, troops massed near Parliament to tighten the noose around the rebels' stronghold where deposed Prime Minister Mahendra Chaudhry and his cabinet have been held hostage since May 19.
They moved to within 300m of the grounds and blocked an exit route with shipping containers. Earlier in the day, they had stopped food and supplies from reaching the rebels, sparking a riot in which three policemen were injured.
Speight's journey to the military headquarters showed his confidence.
The Herald observed him arrive with two of his own unarmed bodyguards on a military bus just before 5 pm.
Soon after, a convoy of cars carrying village chiefs entered the grounds and the parties converged on the officers' mess for talks with Commodore Bainimarama and other senior commanders.
The failed businessman continues to press for a position of power in the military-appointed interim Government that will run the country until fresh elections in up to three years.
Negotiators, who have already caved in to three of his demands, including the ditching of the 1997 non-racial constitution, offered to set up an "advisory panel" for Speight's people to advise the interim Government. He wants more.
"At the end of the day, it's about commitment," said Speight, who is in his early 40s. "Perhaps it's time that the future of this country can be run and led by young guys like me."
Asked whether he would like to be Prime Minister, he replied: "If the vanua [the people] and the Great Council of Chiefs decide they want to ask me to play a part [in Government]."
He said he would not harm the hostages unless anyone from outside tried to intervene.
George Speight talks to IRN's Barry Soper
(10 min).
