A convoy carrying diplomats from Indonesia and Singapore has been attacked in Myanmar.
Local media say the officials came under attack in eastern Shan State on Sunday, but no injuries were reported.
Myanmar's security situation is expected to be high on the agenda at a summit meeting of the Association of Southeast Asian Nations set for Wednesday in Indonesia.
The chair country's president, Joko Widodo, said it was regrettable that the incident happened while the officials were on their way to deliver humanitarian aid.
"It's the people who will suffer, and under these conditions nobody will win," he said.
He stressed his country's efforts to end the fighting in Myanmar won't change. He also called for dialogue to find a solution.
Indonesia is seen as a hard-liner among the ASEAN members as it has strongly urged Myanmar's military to immediately stop the violence in the country.
Attention is on how the incident could affect discussions at the upcoming ASEAN meeting.