An outpost belonging to the Shan State Army-South (SSA-S) in northeastern Burma was burnt down on Sunday by government soldiers, who claimed to be searching for four Burmese “civilians” who went missing at the end of last month, rebels say.

Burmese soldiers raided an SSA-S outpost in Tenghkam village in Namhkam township in northern Shan state on Sunday under the premise of looking for the four individuals – who are believed to be military intelligence personnel – and set it on fire when they could not be found, according to the rebels.

The four went missing in Kawng Waing village-tract, shortly after being seen selling pictures of public figures to locals in the area. The Burmese army later accused the SSA-S of detaining them – an allegation which the rebel group has denied.

“The Burmese army’s Muse-based Tactical Operation Command previously asked us whether we detained the four, assumed to be military intelligence personnel, and to return them if we had. We replied to them that we have neither detained nor seen them,” SSA-S spokesperson, Sai Lao Hseng, told DVB.

“But they said they didn’t believe us and insisted on searching one of our outposts and told us to move out our troops [temporarily] from there. So we moved out, they came for the search and then burnt it down.”

He said the Burmese army has been painstakingly searching for the four since they went missing – which is an unusual response when dealing with missing civilians. On 2 May, troops from 190th and 45th Infantry Battalions went to Tenghka, Nongpeng and Namawe villages in the Kawng Waing village-tract to search for them.

The SSA-S on 6 May sent a letter to the Burmese government’s peace negotiator Union Minister Aung Min, demanding a full and thorough investigation into the incident. There had been no response as of Tuesday.

On 1 May, a brief clash broke out between SSA-S and government troops in southern Shan state’s Kengtong township on the west bank of Salween River when the Burmese troops entered the group’s territory – apparently to inspect a gold mining and logging operations in the area – but without giving any advance notice.

Despite reaching a tentative ceasefire agreement in December 2011, the SSA-S and the Burmese army have engaged in dozens of clashes since. Sai Lao Hseng said the group has sent letters to the Burmese government after each clash, but rarely received a response. He said that the Burmese army has not been very cooperative in the peace process and warned that it could lead to further distrust and violence.

The SSA-S is one of Burma’s largest armed ethnic groups, and has been fighting for greater autonomy and ethnic rights in Burma for over half a century.