Man stabbed in alleged botched hold-up

A man who allegedly tried to rob a newsagent in Sydney's west has ended up with stab wounds after a scuffle with a shopkeeper.

Police say a man in his 30s assaulted a shopkeeper in the newsagency at Werrington on Monday afternoon.

The man allegedly grabbed some cash before a scuffle broke out with the shopkeeper.

The alleged thief suffered stab wounds but managed to flee the shop.

He was stopped nearby and taken by ambulance to Westmead Hospital.

Police say the man is under police guard and in a serious condition.

"The shopkeeper is currently assisting police with their inquiries," NSW police said in a statement.

The shopkeeper was not injured.