An ice-affected taxi driver has been caught on the Tullamarine Freeway.

The 37-year-old Noble Park man tested positive for the drug when he was stopped by police while heading towards the city about 8.30pm on Thursday night.

Victoria Police spokeswoman Creina O'Grady said a search of his cab revealed two bags of white powder believed to be methamphetamine.

Ms O'Grady said police had been alerted to the driver's behaviour days before the arrest by a member of the public who had recorded footage of the man allegedly smoking ice in his cab.

The driver is expected to be charged with drug driving, possession of a drug of dependence and failing to wear a taxi driver's uniform.