Major roads have been blocked after a huge blaze broke out in Melbourne’s southeast.

A supermarket in Dandenong was evacuated after a fire erupted on its roof before 7pm on Thursday night.

About 120 firefighters battled flames until early Friday morning before it was finally contained and an investigation has been launched to establish the cause.

Ambulance crews, Victoria Police, and the Environment Protection Authority were also at the scene.

Traffic was congested in the area early on Friday after the Princes Highway was closed between Clow Street and Foster Street, and between Walker Street and Langhorne Street.

Roads remain blocked in Lonsdale Street.

Fire Rescue Victoria said the blaze was now under control.

“The fire spread quickly across the building threatening neighbouring properties,” a spokesperson said.

“More than 31 appliances and 120 firefighters contained the fire to the building of origin.

“A community alert was issued due to the amount of smoke and activity in the local area.”

The Country Fire Authority said it was also investigating the incident.

– AAP