The UN's special envoy to Myanmar, Ibrahim Gambari, was expected in Yangon on Saturday for talks with the country's ruling generals amid a row over the threatened expulsion of another key diplomat.
Gambari's visit comes amid conflicting signals from the junta over its willingness to reform, in the wake of mass street protests against the ruling regime in Yangon that led to at least 13 deaths and the detention of thousands.
Myanmar's ruling generals abruptly announced late on Friday that the mission of the UN's most senior official in Yangon, Charles Petrie, will not be renewed.
Internet links in the isolated country, cut by the junta on Thursday, remained down for the third straight day, restricting access to international websites in an apparent attempt to limit the flow of information before and during Gambari's visit.
The regime's latest heavy-handed gestures have blunted early optimism over Gambari's arrival, following this week's release of 165 people arrested during September's wave of protests.
The move to expel Petrie from Myanmar, where he has worked since 2003, could complicate Gambari's already difficult mission, with some warning that the row will sidetrack his reform discussions with the junta.
"The danger is that Gambari will spend his time talking about the UN's role in Burma instead of the need to end the crackdown and bring real reform," said Brad Adams, Asia director for the New York-based pressure group Human Rights Watch.
Current ASEAN-bloc chair Singapore said Saturday it was "deeply disappointed" by Myanmar's decision on Petrie, while the United States, one of junta's staunchest critics, said it was outraged.
"I hope that this is not an effort by the regime to deflect from the mission" of Gambari, said the US ambassador to the UN, Zalmay Khalilzad.
A UN spokeswoman said the organisation has "full confidence" in Petrie and his team, and that it has instructed Gambari to raise the issue with the Myanmar government.
"He has not been declared persona non grata," spokeswoman Michele Montas said of Petrie.
When reached by phone in Yangon on Saturday, Petrie said he would meet with Gambari upon the envoy's arrival but would not comment on the junta's move against him.
Ahead of Gambari's visit, some experts said the international scrutiny faced by the junta since the crackdown could pave the way for a meeting between Aung San Suu Kyi and the regime's top general Than Shwe, a key demand of the international community.
"Than Shwe does not ... want to have dialogue with Aung San Suu Kyi, but current international pressure and sanctions may force him to have talks," said Thai-based Myanmar analyst Aung Naing Oo.
Others, though, see any concessions made by the junta as an attempt to give the impression it is trying to meet demands for reform without ceding any real power.
"The junta is trying to make some concessions. But in terms of substance, I don't think the concessions are real," said Win Min, a lecturer at Payap University in Chiang Mai.
He added that any talks with the opposition would not represent real progress towards national reconciliation.
The inclusion of pro-democracy leader Aung San Suu Kyi's National League for Democracy (NLD) party in the political process is largely seen as crucial for Myanmar's gradual transition to democracy.
Aung San Suu Kyi has spent 12 of the past 18 years under house arrest, and with other NLD officials in prison the party has been excluded from any debate over Myanmar's future.
Aung San Suu Kyi's NLD won elections in 1990 by a landslide but was never allowed to rule.
UN Secretary General Ban Ki-moon said earlier this week that Gambari's visit "will have to bring substantive results," including the release of those detained during the protests.