Coronavirus restrictions will be reimposed across greater Melbourne after a fifth case of COVID-19 was confirmed, linked to the outbreak in the city’s north.

Acting Premier James Merlino said the new case, confirmed on Tuesday morning, was a man in his 60s.

He is a household contact of the first case linked to the City of Whittlesea that was confirmed on Monday – although he has reported being symptomatic earlier than the initial infection.

“He is isolating, as are his household contacts,” Mr Merlino said.

Mr Merlino also announced new restrictions in response to the outbreak, which will take effect from 6pm Tuesday.

Tweet from @covidliveau

Private home gatherings will be limited to five visitors a day, public gatherings will be capped at 30 and face masks must be worn indoors, including in shopping centres and workplaces.

Schools and workplaces will stay open and there are no changes to density rules. Mask must be worn in secondary schools, and in primary schools for the staff.

Restrictions will remain in place for Greater Melbourne until June 4.

The state’s chief health officer Brett Sutton said “at the moment” the restrictions will continue until June 4.

“They will be reviewed right through that period,” he said.

“This is a responsible step we need to take to get on top of this outbreak,” Mr Merlino said.

He confirmed genomic sequencing had found the Whittlesea outbreak was “closely related” to a man in nearby Wollert, who tested positive earlier in May after returning from hotel quarantine in South Australia.

Health authorities have identified 10 exposure sites as they race to contain the COVID-19 outbreak.

Four new cases – two men in their 30s and 70s, a woman in her 70s and a pre-schooler across three households in the City of Whittlesea – were confirmed in a cluster in Melbourne’s northern suburbs on Monday afternoon.

Victorian health authorities tweeted confirmation of the four earlier cases on Tuesday morning. The fifth case was confirmed at a later media briefing.

Tweet from @VicGovDH

More household contacts of this week’s cases have been put into isolation and have so far tested negative to the virus.

Victoria has 13 active cases, with the rest in hotel quarantine.

Tier One exposure sites (meaning people must get tested, isolate for 14 days) include:

• Nando’s Epping and Woolworths Epping North
• Jump! Swim Schools Bundoora
• Highpoint Shopping Centre

Futsal Brunswick, Epping North Shopping Centre, House and Party at Epping, Urban Diner Food Court at Pacific Epping Shopping Centre, Shells Coles Express Reservoir and BT Connor Reserve are tier two sites – meaning affected people must get tested and isolate until they have a negative result.

• Read the full list of exposure sites here

Channel Nine reported earlier a test site at Epping, in Melbourne’s north, had closed because of demand, while there was a two-hour wait on Tuesday morning at the Royal Showgrounds, in the city’s inner-north-west.

The health department last week admitted it had listed the wrong supermarket as an exposure site when the Wollert man tested positive earlier in May.

State Opposition Leader Michael O’Brien said on Tuesday that Victorians were nervous after the government blundered on the supermarket exposure site and “seems to be making some pretty basic errors” on contact tracing.

“The last thing Victoria can afford is going back into lockdown,” he said.

Professor Sutton has said the first Whittlesea man was carrying a high viral load and warned the community to brace for more possible cases.

Testing sites across Greater Melbourne

Testing sites serving the city’s north are straining to cope with demand as people heeded public health advice over the new outbreak.

Health Minister Martin Foley said 26 sites would be operating on expanded hours on Tuesday, including the Melbourne Showgrounds, which would operate as a four-lane drive-through testing site until 8pm.

“We are finalising a number of other pop-up sites that will be communicated on our website as they open to deal with expected demand,” he said.

The ABC reported there were lengthy waiting times at several sites, including a four-hour wait at the Victoria University site at St Albans, and three hours at Royal Melbourne Hospital.

All domestic borders remain open, despite most states and territories issuing updated travel advice for recent Victorian arrivals.

This week’s outbreak snapped Victoria’s 86-day streak without a locally acquired case.

-with AAP