Three teens arrested after fire 'deliberately lit' in Sydney

Three teenage boys have been arrested after a grassfire was allegedly started in Sydney's south-west last night.

A passing motorist alerted authorities when he saw the fire in bush land off The Northern Road at Harrington Park about 5.30pm yesterday.

Follow the bushfire crisis here

Firefighters attended the incident and had the fire was extinguished by 6.15pm.

After receiving information from the public, police searched the area and arrested two boys, aged 15 and 16, near Harrington Parkway.

A third teen, aged 15, was arrested a short time later.

All three were taken to Narellan Police Station and have been interviewed by police in the presence of their support people.

They are eligible to be dealt with under the Young Offender's Act.

Three mobile phones and other items have been seized for forensic examination.

The incident follows other arrests in NSW and Queensland last week after bushfires were started.

Last Friday a 51-year-old man was charged with lighting an out-of-control fire in the NSW Northern Tablelands in order to protect a cannabis crop.

Earlier in Queensland, a 16-year-old boy was charged over a fire that destroyed homes and livelihoods near Yeppoon.

Two teenage boys from NSW are accused of lighting a fire with paper, dry leaves, vegetation and a cigarette lighter on the state's Far North Coast.

And in a separate incident, a 34-year-old man was charged last week after allegedly setting off a firework which started a fire in a Sydney park.