Melbourne, May 27 (IANS): Australian Prime Minister Scott Morrison on Thursday pledged extra vaccines and defence force support for Victoria, country's second-most populous state, which will be placed under a seven-day Covid lockdown from midnight.

The lockdown will be enforced after authorities identified 10,000 primary and secondary contacts linked to a Covid-19 outbreak in the state capital Melbourne's northern suburbs, reports Xinhua news agency.

Responding to the lockdown announcement, Morrison praised the "tremendous job" of contact tracers and promised "every support" available for the state including 130,000 additional vaccine doses.

"The next seven days in Victoria will be very challenging, and of course we are very mindful of the distress and the difficulty that this will impose upon people right across Victoria," he said.

Announcing the restrictions on Thursday, when 12 new local cases were reported, Acting Victorian Premier James Merlino said the lockdown may have been avoided if the national vaccine program was effectively rolled out and specialized quarantine facilities were established for returned international travellers.

Anthony Albanese, leader of the opposition Labor Party, said Victoria "never should have been put in this situation" because the federal government should have fixed quarantine many months ago.

According to Albanese, it was the 17th Covid-19 outbreak linked to hotel quarantine.