YANGON, Myanmar (AP) — Some ethnic rebel groups in Myanmar are expressing concern that a critical peace conference with the government has been scheduled for too early a date, limiting the opportunities for all parties to participate and jeopardizing the chances of success.

State Counselor Aung San Suu Kyi, Myanmar’s de facto leader, announced this week that talks will begin Aug. 31 on ending more than five decades of strife with ethnic minorities seeking greater autonomy.

Lamai Gum Ja of the Kachin Peace Creation Group said Friday that the ethnic groups need more time to prepare for the talks. He and several colleagues complained that the government set the date without consulting them, and that fighting continued between government troops and the Kachin and Shan minorities even after the meeting was announced.

“We have said many times that the government needs to work on negotiations to stop the offensive attacks by the military on the ground,” said Khu Oo Reah, general secretary of the United Nationalities Federal Council ethnic alliance and vice chairman of the Karenni National Progressive Party.

Suu Kyi, whose National League for Democracy party succeeded a military-backed government in March, has called the August meeting the 21st Century Panglong Conference, a reference to a 1947 Panglong Agreement that was signed by her father, Gen. Aung San, and ethnic minority groups. Aung San was assassinated before the country became formally independent from Britain, and ethnic groups generally hold his successors responsible for not honoring the 1947 pact, which would have guaranteed them more autonomy.

Myanmar’s previous military-backed government signed cease-fires with several — but not all — rebel groups, but most insist that a political settlement granting them further rights is key to reconciliation and peace.

It remains unclear if all groups, including those who have not signed a cease-fire, will take part in the conference. The ethnic minorities believe that only a comprehensive agreement including all can succeed.