Firefighters have extinguished blazes on both sides of the ACT-NSW border, with no damage to property and no injuries reported.
Multiple crews from the ACT Rural Fire Service and ACT Fire and Rescue put out a grass fire near Oaks Estate about 2.40pm.
The Emergency Services Agency said the blaze, which burned dry grass near the Molonglo River between Pialligo Avenue and Oaks Estate Road, was 0.71 hectares in size.
While the cause was yet to be determined, it was considered suspicious and would be referred to ACT Policing for investigation.
The agency said the area would be patrolled in the coming days.
Across the border, two Fire and Rescue NSW crews spent about an hour fighting a two-hectare grass fire in Queanbeyan.
A Fire and Rescue NSW spokesman said crews extinguished that fire about 1pm, supported by tankers from the ACT.