The Association of Southeast Asian Nations has led diplomatic efforts to end the chaos unleashed by last year's putsch in Myanmar, which triggered mass protests and a deadly crackdown on dissent.

Cambodian foreign minister Prak Sokhonn, its new special envoy to the country, told a meeting of the bloc's foreign ministers he planned to visit in March and meet with top junta officials.

He added a request to be allowed to meet with members of a "National Unity Government" dominated by lawmakers from Aung San Suu Kyi's ousted party that is working to overthrow the junta.

"If Naypyidaw is not speaking with the NUG... let the special envoy be the bridge," he said, referring to Myanmar's capital.

The junta has declared the NUG "terrorists" and jailed several high-ranking members of Suu Kyi's party.

Most NUG members are in exile or in hiding and Prak Sokhonn gave no details on where or when any future meeting might take place, or whether he had discussed his plans with the junta.

The junta did not respond to a request for comment.

Myanmar's top diplomat was barred from Thursday's meeting in Phnom Penh over a lack of progress in defusing violence, although Prak Sokhonn said junta representatives had been allowed to listen in on discussions.

More than 1,500 people have been killed and over 12,000 arrested in a military crackdown since the coup, according to a local monitoring group.