Police have arrested a man following a large suspicious grassfire on Melbourne outskirts.

The 34-year-old man, of no fixed address, was arrested in Vearings Road about 12.50pm and is assisting police with their inquiries.

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The fire started in grassland along the Hume Freeway and Cooper Street about 10.15am.

Firefighters at a fast moving grass fire in the Epping area.

No one was injured in the blaze and no properties were damaged.

Just after 2pm fire crews stopped the spread of the fire that threatened homes and businesses.

The CFA has downgraded its watch and act message for the Epping fire to an advice message.

“There is currently no threat to communities, but you should continue to stay informed and monitor conditions,” the CFA says.

Smoke is still visible from nearby communities and roads and the Hume Freeway remains closed.

Fire crews will remain on scene overnight and police are keen to speak to any witnesses.