Four of Victoria's new COVID-19 cases are of the highly infectious Delta variant.
Health Minister Martin Foley on Monday confirmed four of the state's 11 new cases were linked to the state's outbreak of the Delta variant, also known as B.1.617.2, which began in the suburb of West Melbourne.
The cases are three children and an adult. It brings the total number of cases in the outbreak to 14.
Four of the new cases are linked to the city's outbreak of the Kappa or B.1.617.1 variant, which began in the City of Whittlesea and has spread to several locations across Melbourne, including Port Melbourne.
The outbreak now totals 33 active cases in Whittlesea and 31 in Port Melbourne.
The remaining three cases are linked to an outbreak of the Kappa variant at the Arcare Maidstone aged care facility in Melbourne's northwest, two of which were announced on Sunday.
The additional case is an aged care worker.
State testing commander Jeroen Weimar said more than 5800 people were quarantining after coming into contact with a positive case, while there were 350 exposure sites across Victoria.
About 1000 people had ended quarantine following a negative day 13 test, he said.
Authorities still don't know how the Delta variant has spread in Melbourne.
Victoria's Chief Health Officer Brett Sutton said authorities were combing through genomic sequencing data from across the country for answers.
The virus is suspected to have leaked from hotel quarantine or from a returned traveller who was provided with an exemption to isolate at home.
Among those allowed to quarantine at home are foreign diplomats.
Asked if a diplomat may have spread the virus, Professor Sutton replied: "We simply don't know. I wouldn't rule anything in or out.
"We are obviously checking against everyone who is tested and diplomats should be tested as well."
Professor Sutton said about 10 people had received an exemption to quarantine at home in Victoria since the beginning of April.
He said with no new exposure sites linked to the 11 new cases, Melbourne's lockdown was on track to end at 11.59pm on Thursday.
But Professor Sutton ruled out a return to the relaxed restrictions in place before the outbreak.
"It is certainly not a snap-back to large gatherings and a full MCG," he said.
"It's not something I can speak to now. It's early days still. It's frustrating, people want to know what things will look like three days from now.
"(But) we see different changes every day and they can be something from left field."
Some 24,265 Victorians were tested on Sunday and 17,719 received a vaccine dose at state-run sites.
Federal Health Minister Greg Hunt on Sunday announced an additional 100,000 vaccines were being made available for Victoria.
The federal government has also extended its suspension of JobSeeker mutual obligation requirements until 15 June.
Meanwhile, the state government has announced a $30 million package of food and support payments for communities disproportionately affected by the latest lockdown.
