Amber alert for missing Queensland kids

Queensland police have issued an amber alert for a six-year-old boy and a four-year-old girl missing from Harristown in Toowoomba who "may be at significant risk".

The police force says the children are with 30-year-old Casey Allwood who's travelling in a 1999 white Toyota Camry sedan with Queensland registration 759 KMD.

The woman is described as being Caucasian, 160 centimetres tall with a slim build, blonde hair and brown eyes.

The car was last sighted travelling eastbound at Gatton about midday on Sunday.

"The woman may be travelling south but also has connections in the Toowoomba and Bundaberg areas," Queensland police said in a statement.