Fire breaks extinguished in Sydney's south, as crews work to keep Northern Beaches fire under control

A grassfire burning in Sydney's south has been extinguished.

The blaze on the Malabar Headland had reignited after dying down overnight.

The small grass fire started at about midnight.

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It was extinguished two hours later, but later flared up again.

Crews from Fire and Rescue NSW were tackling it.

Meanwhile, residents across the city have woken to a thick blanket of smoke after a bushfire on the Northern Beaches.

The fire which raged through 100 hectares of bushland is contained after burning through the night near Cromer Heights, Beacon Hill and Oxford Falls.

Crews are still working to stop it escalating.