MYANMAR-THAI BORDER (Reuters) - Thousands of people sporting traditional ethnic costumes and Karen rebel fighters showing off their guns marched, sang and danced last week to celebrate 70 years since the start of the struggle for greater autonomy from Myanmar.

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Boasting more than 5,000 soldiers, the Karen National Union (KNU) is one of the most powerful and best-established of the country’s myriad militia groups that have fought the government since shortly after Myanmar gained independence in 1948.

The KNU’s parade served as a reminder that the biggest priority of the Aung San Suu Kyi’s administration - ending decades of ethnic wars - remains elusive.

Suu Kyi has struggled to make progress with autonomy-seeking ethnic minority rebels, who have accused her government of a high-handed approach and ignoring their grievances and aspirations.

The KNU celebrations took place at a remote base in the mountains straddling the Myanmar-Thai border.

“The history of the revolution for 70 years is a very rough one. As someone who has been involved in the revolution for 50 years, I can say it’s very tough and the sacrifices were very big,” Man Nyein Maung, one of the KNU’s executive members, told the Irrawaddy online news magazine.

The celebrations lasted several days and nights with a folk dance competition and theater performances before a military parade and speeches on a cloud-shrouded, dusty parade ground carved from the hills at the crack of dawn.

A banner hoisted above the grounds listed some of the group’s political demands, including calls to “retain our arms” and to “decide our own political destiny”.

One of the dance groups was made up of women wearing yellow scarves, with their hair tied in a bun and an exposed fringe. Their yellow shirts with green patterns contrasted with their white face powder and red lipstick.

The performers mingled with villagers and soldiers of the Karen National Liberation Army, the KNU’s armed wing. The men smoked cigarettes as they watched, some with heavy bullet belts draped around automatic rifles, and with insignia in red, white and blue displayed on their uniforms.

The KNU signed a ceasefire with the government in 2012 after more than six decades of conflict that had driven tens of thousands of refugees into Thailand.

Some have come back although about 100,000 remain in the refugee camps on the other side of the border, according to the United Nations. While major clashes have been avoided, the KNU’s relations with the Myanmar army remain tense.

Suu Kyi has struggled to secure peace elsewhere in the country and long-simmering conflicts in the north and the west have intensified in recent years.

In 2017, a military offensive drove out 730,000 Rohingya Muslims from the western state of Rakhine to Bangladesh, creating one of the world’s largest refugee crises.