Reports from Burma say military authorities have signed an order authorising the release of pro-democracy leader Aung San Suu Kyi.
But hopes she would be freed on Friday were dashed: there has been no official confirmation of a release order.
A leader of her NLD party told 2,000 supporters gathered at its headquarters to go home and return on Saturday.
Ms Suu Kyi has been detained for 15 of the past 21 years, and her house arrest term expires on Saturday.
There has been increased police activity outside her house in Rangoon, Burma's largest city, but no formal statement from military officials.
However, Ms Suu Kyi is not expected to accept a conditional release if it excludes her from political activity.
The 65-year-old was originally due to be released last year, but a case involving an American who swam across Inya Lake to her home, claiming he was on a mission to save her, prompted the latest 18-month detention.
The BBC is banned from reporting in Burma but correspondent Alastair Leithead is monitoring developments from the capital of neighbouring Thailand, Bangkok.
He says a number of sources inside Burma have told the BBC that documents authorising Ms Suu Kyi's release have been signed.
Officials have reportedly visited her home in University Avenue to deliver them.
About 2,000 of her supporters gathered at NLD headquarters in anticipation of her release. Some wore T-shirts saying: "We stand with you."
"Young and old, NLD members and non-members are gathering here with excitement to welcome her. At one point, we got the news that she was released and we all shouted with joy," Yazar, an NLD youth leader, told the BBC's Burmese service.
But by early evening a party leader told people to go home because it seemed unlikely she would be freed on Friday.
A man waiting outside the gate to Ms Suu Kyi's home said little had changed.
"People are waiting in groups here and there, maybe more than 100 in total - many of them are journalists," he told the BBC. "Security is normal as usual. No increase. The gate is closed as before, that's it."
Ms Suu Kyi's lawyer said: "There is no law to hold her for another day. Her detention period expires on Saturday and she will be released."
"They should release her for the country," Nyan Win added.
Earlier this week, he told the BBC that she would "not accept a limited release".
"[It] must be unconditional. As we all know, she never accepted limited freedom in the past."
Nyan Win said she would meet with the NLD's central committee, members of the media and the public once she was freed.
The British ambassador to Burma, Andrew Heyn, has told the BBC that the UK and EU are pressing hard for Ms Suu Kyi's unconditional release, and that her freedom would have a "significant impact".
The increasing speculation that the ruling generals may sanction Aung San Suu Kyi's release follows the country's first elections in 20 years on Sunday.
On Thursday, state media announced that partial results showed that the biggest military-backed party, the Union Solidarity and Development Party (USDP), had secured a majority in both houses of parliament.
The USDP had won 190 of the 219 seats so far declared in the 330-seat lower House of Representatives, and 95 of 107 seats in the 168-seat upper House of Nationalities, the reports said.
Those elected included the leader of the USDP, Prime Minister Thein Sein, who retired from the military as a general in April to stand.
The junta has said the election marks the transition from military rule to a civilian democracy, but the opposition, many Western governments and human rights groups have said the election was neither free nor fair.
The NLD - which won the last election in 1990 but was never allowed to take power - was ordered to dissolve after refusing to take part.
A quarter of seats in the two new chambers of parliament will be reserved for the military. Any constitutional change will require a majority of more than 75% - meaning that the military will retain a casting vote.