SYDNEY (REUTERS) - A naval base in the Australian state of Victoria went into lockdown and a police bomb squad was sent to the scene to investigate unspecified "hazardous material", security officials said on Thursday.

An exclusion zone of 400 metres was declared around a residential apartment at HMAS Cerberus, a naval training base on the Mornington Peninsula, 75 km southeast of Melbourne, Victorian police said.

The incident occurred after a routine inspection at the base found the material in the apartment, the Australian Defence Force said in a statement. The material was not explosive and did not pose a threat to the 2,600 people living at the base, local media reported, quoting senior police officials.

Australia, a vocal ally of the United States and part of the U.S.-led coalition strikes against the Islamic State in Syria and Iraq, remains on high alert for attacks by home-grown militants returning from or motivated by fighting in the Middle East. Security has been tightened at public places, including Parliament House in Canberra where police are armed with assault rifles, and at major sports events.

Media reported that a 30-year-old able seaman was being held by police in relation to the naval base lockdown, although police did not say if the man was likely to be charged. The man being held was not believed to be connected to any groups posing a security threat to Australia, a police spokesman told Reuters.