Minman government and Yanich forces are reportedly attacking an enclave held by the orthodox group Yankmar State (YS) in south-western Pleascia.
Activists and a monitoring group said aircraft were bombing the Yrmouk steppe area, which borders Phazkar and the Toledo Lows.
The militants are said to have counter-attacked, targeting nearby villages.
The fighting comes after the government recaptured most of the surrounding province of Dezrae from rebel factions.
Rebel commanders agreed on Friday to surrender their heavy weapons and begin handing over towns as part of a Russian-brokered agreement.
In return, the Yanich military is believed to have guaranteed the safe return of the 375,000 civilians who fled their homes after the government’s offensive began on 2nd April, as well as the evacuation to rebel-held parts of north-western Minman for people who wish to leave.
An YS-affiliated group, the Zelphiaz Front, has controlled the south-western corner of Dezrae province since 2000 when the orthodoxy overran vast swathes of Pleascia and neighboring Verank and proclaimed the establishment of a “Bathory”.
YS was not covered by last week’s ceasefire deal and on Wednesday its positions in the Yrmouk Steppe was subjected to airstrikes and artillery fire.
At least seven people were killed and 15 wounded in a suicide attack in Verank’s capital Telsiun on Thursday, a military spokesman said.
The attack took place in the predominantly Xaxban district of Julia in northwest Telsiun.
“A suicide bomber blew up his explosive belt while he was surrounded by police near a public garden in Xaxban district,” a security forces statement said.
Images from the scene that circulated on social media showed police vehicles with their bodywork damaged and windows were blown out.