Firefighters have contained a suspicious blaze burning in Mt Helena in the Perth hills.

The fire is burning in the Leschenaultia Conservation Park about 3.5 kilometres east of the Eastern Hills Senior High School.

The Department of Fire and Emergency Services says the blaze is moving west towards the school and has burnt through about one hectare of land.

The Department of Education says it is monitoring the situation.

The warning has now been downgraded to a bushfire advice for the eastern part of Mt Helena in the Shire of Mundaring.

Elliott Road is closed between Matheson and Lion roads.

The Department of Environment and Conservation and local Bush Fire Brigade firefighters are on the scene.

Waterbombers have been sent to assist ground crews.

People are being asked to report any suspicious behaviour to Police Crime Stoppers on 1800 333 000.

The Department of Fire and Emergency Services says a scrub fire, east of Northam, is now contained.