Aung San Suu Kyi snubbed Mr Gambari during his last visit in August
Burma's detained pro-democracy leader Aung San Suu Kyi has told a UN envoy the secretary general should not visit until political prisoners are freed.
During their first meeting for nearly a year, Ms Suu Kyi told Ibrahim Gambari there was no rule of law, citing harsh jail terms handed down to activists.
Mr Gambari is trying to revive reconciliation talks between the military government and the opposition.
Aung San Suu Kyi has spent much of the past 19 years under house arrest.
She snubbed Mr Gambari during his last visit in August because of his failure to extract any meaningful concessions from Burma's military rulers.
Members of Ms Suu Kyi's National League for Democracy party (NLD) said she told the envoy that "she was ready and willing to meet anyone, but she could not accept having meetings without achieving any outcome".
Mr Gambari's previous visit to Burma attracted little praise
NLD spokesman Nyan Win said she also warned that UN Secretary General Ban Ki-moon should not visit Burma until after herself, the NLD's deputy leader and other political prisoners were released.
The Nobel Prize winner also criticised the harsh prison sentences recently given to more than 250 people.
"She pointed out that the long prison sentences, such as 65 or 100 years, were handed down with no defence and no lawyers allowed - even lawyers themselves were sentenced," Nyan Win said.
Mr Gambari, who arrived in Burma on Saturday for a four-day visit, has held talks with the foreign minister but it is unclear whether he will be allowed to meet the head of state, General Than Shwe.
The UN envoy told diplomats that his objectives were to urge the release of political prisoners, discuss the country's ailing economy and revive dialogue between Ms Suu Kyi and the junta.
Mr Gambari's seventh trip to the country comes amid criticism that he has failed to achieve Ms Suu Kyi's release or any other discernible progress from his diplomacy.
BBC South East Asia correspondent Jonathan Head says that even if Mr Gambari managed to meet Than Shwe, it was unlikely anything could be achieved.
The military is pushing ahead with a tightly-controlled election next year, which is guaranteed to leave it holding most of the levers of power, he says.
Burma's ruling generals have continued to suppress dissent since crushing mass pro-democracy protests led by monks in September 2007.
Human rights groups say the number of political prisoners being held has doubled to 2,100 since then.
The NLD won a general election in 1990 but the junta refused to allow the party to assume power.
The junta says it will hold elections in 2010 under a revised constitution, a process which the opposition sees as fundamentally flawed.
In recent months, the generals have further consolidated their grip on power, pushing through a constitution which reserves 25% of the seats in any future parliament for the military.