Sydney, Oct 22 (IANS): A man has been killed in a car crash with a vehicle that police were following in Sydney on Tuesday, police said.

Police in the Australian state of New South Wales (NSW) declared a critical incident after the motorist died in the crash in the suburb of St Mary's, approximately 40 km west of Sydney's central business district.

NSW Police said in a statement that two officers in a police vehicle stopped near a grey sedan at about 4 a.m. local time on Tuesday when the driver of the sedan allegedly accelerated away.

Police lost sight of the vehicle but followed and found it had crashed with a silver hatchback. The driver of the hatchback, a man believed to be aged in his 40s, died at the scene, Xinhua news agency reported.

The 43-year-old driver of the sedan allegedly fled the scene on foot but was arrested a short time later and taken to hospital under police guard.

"A crime scene has been established and a critical incident team from North Shore Police Area Command is investigating the circumstances surrounding the incident," NSW Police said.

The Greater Western Highway, a major road linking Sydney with the city's centre, has been closed in both directions.

Anyone with dash cam or CCTV footage of the incident has been urged to contact police.