It is feared properties have been destroyed in an out-of-control blaze that burnt through southern NSW on Sunday.

The grassfire started just before 6pm (AEDT) on Sunday night and quickly scorched almost 200 hectares of grassland along the Hume Highway just south of Yass.

More than 40 trucks and three aircraft were working to contain the blaze, which shut northbound lanes on the highway for a couple of hours.

“It escalated very quickly as grassfires do,” Rural Fire Service (RFS) spokesman Joel Kursawe told AAP on Monday.

Firefighters got the blaze under control at about 10pm, with the watch and act alert cancelled.

Overnight crews stayed on site, doing patrols and mopping up.

Firefighters will be scouring the area throughout Monday to see what damage has been done.

“We have unconfirmed reports that property or properties have been destroyed,” Mr Kursawe said.

But he said it could be a house, an outbuilding or simply a shed.

Crews are expecting that there will be a lot of damage to farm fencing in the area.