Perth boy critical after car hits tree

A 14-year-old boy has suffered a serious head injury when a car allegedly being driven by an alcohol-affected man crashed in Perth's southern suburbs.

The teen was the front passenger in the sedan that veered off a Hope Valley road and hit a tree on Monday evening.

The rear passenger, a 25-year-old man, was taken to hospital with minor injuries and later released.

The driver, a 26-year-old man of no fixed address, was arrested and charged with excess .05 after a breath test.

He was refused bail and is due to appear in the Rockingham Magistrates Court later on Tuesday.