A MAJOR Victorian naval base was locked down and a seaman arrested today amid an explosives scare.

A 400m exclusion zone was set up around the HMAS Cerberus base at Crib Point, on the Mornington Peninsula, amid fears of an blast.

Police bomb response officers called to the scene later found the materials were hazardous but not explosive.

They were discovered in barracks at about 11am.

The 30-year-old seaman was arrested soon after and was being questioned by investigators at the base late today.

“He is arrested because of the nature of the hazardous material and some concern we have with regard to them,” Supt Neil Paterson said.

The Defence Department had earlier said the materials were discovered during a routine inspection.

Both entrances to HMAS Cerberus closed & guarded by security. pic.twitter.com/RoDtn2o71X — Rita Panahi (@RitaPanahi) October 16, 2014

“It doesn’t not appear to be any explosive materials but rather they are hazardous material,” Supt Paterson said.

“The materials involved should normally not be in barracks and are hazardous in nature.”

He said the amount of material found was not large.

HMAS Cerberus is a Navy training establishment where 6000 personnel are trained each year, averaging 800 trainees at a time.

It covers 1517 hectares and is 70 kilometres from Melbourne near Crib Point, Western Port Bay. HMAS Cerberus has training and recreation facilities, two chapels, and small marina.