Fire fighters have brought a mulch fire in Canberra's north under control.

The blaze began at Canberra Sand and Gravel on Parkwood Road in Holt and measured 50m by 50m.

Nine fire tankers and crews were called in to break up the mulch, using water and foam to put out the fire.

About 80 per cent of the fire had been extinguished by 12.30pm and no property was under threat.

The cause is unclear.