Myanmar's junta refused on Friday to let a UN envoy visit the country, despite mounting international efforts for a diplomatic solution to the post-coup crisis.
The UN's special envoy for Myanmar, Christine Schraner Burgener, is on a tour of Asian countries aimed at charting a path out of the turmoil engulfing the country.
It comes amid growing international concern at events in Myanmar, rocked by daily protests since the military ousted civilian leader Aung San Suu Kyi and seized power on February 1.
Burgener starts her trip in Thailand and will also visit China, though exact details and timings for her trip have not been confirmed.
UN officials say Burgener wants to travel to Myanmar for face-to-face meetings with the generals, but a junta spokesman ruled it out.
"We have not permitted this. We also have no plan to allow it at this moment," spokesman Zaw Min Tun told AFP.
Burgener confirmed the junta had said no to her visit.
"I regret that Tatmadaw answered me yesterday that they are not ready to receive me," she said on Twitter, using the official name for Myanmar's military.
"I am ready for dialogue. Violence never leads to peaceful sustainable solutions," she added.
- Hundreds killed -
At least 614 civilians have been killed in the military's crackdown on protests and nearly 3,000 arrested, according to the Assistance Association for Political Prisoners, a local monitoring group.
There was more bloodshed on Friday, with rescue workers reporting at least four people killed in the early morning when security forces broke up protest barricades in the city of Bago, 65 kilometers (40 miles) northeast of Yangon.
Local media reports said the fighting continued during the day, and the death toll could be higher.
UN rights officials say the military is making increasing use of heavy weaponry including rocket-propelled and fragmentation grenades, heavy machine guns and snipers.
The military insists it is responding proportionately to what it says are violent protesters.
At a news conference in the capital Naypyidaw, officers displayed guns they said were seized from demonstrators.
The protest movement has sought to disrupt the military's ability to run the country by encouraging key public workers such as doctors and railway staff to stay at home.
Zaw Min Tun, the military spokesman, accused medical staff of "killing people in cold blood" by refusing to work.
"Now the public hospitals cannot function because health workers are breaking their ethics," he told reporters.
The violent response to protests has drawn intense international criticism and on Thursday Washington imposed another set of sanctions, this time on Myanmar's state gem company, as it seeks to deprive the junta of income.
- Diplomatic push -
UN spokesman Stephane Dujarric said Burgener wants to open dialogue with the junta to help end the chaos in Myanmar.
As well as China -- a key player with historical links to the military and which more recently cultivated close relations with Suu Kyi -- she also plans to visit member countries of regional bloc ASEAN.
An ASEAN summit on Myanmar is scheduled for the end of the month, but diplomats say the bloc is deeply divided over the crisis.
"At one end, there are Thailand, Laos and Cambodia, who are in the mode of 'back off, there's nothing to see, it's a question of internal politics,'" one diplomat said, while Singapore, Malaysia and Indonesia are open to a more active role for ASEAN.
In a further sign of discreet but growing diplomatic outreach, there have been reports that China has opened contacts with the CRPH, a group representing the ousted civilian government.
A foreign ministry spokesman in Beijing said China was in contact with "all parties" as part of efforts to restore stability.
The UN Security Council is set to meet informally Friday to hear from Myanmar lawmaker Zin Mar Aung on behalf of the CRPH.
Earlier this week the CRPH, which says it has amassed nearly 300,000 pieces of evidence showing rights abuses by the junta, began talks with the UN's Independent Investigative Mechanism for Myanmar.
The military has defended its seizure of power, pointing to what it said was fraud in November's election, which Suu Kyi's National League for Democracy won comfortably.
- Journalists arrested -
When it took over, the military imposed a one-year state of emergency, but spokesman Zaw Min Tun told CNN this may be extended by up to a year, though he insisted elections would then be held.
The junta has steadily choked off communications, throttling mobile data and imposing nightly internet shutdowns, while raiding newsrooms and arresting journalists.
Local news outlet Mizzima reported Thursday that its co-founder Thin Thin Aung and another former employee were detained.