The seafarer arrived in New Zealand on January 24 and was given a departure swab ahead of shore leave.
A second person who arrived on January 29 had travelled through Singapore and was found positive for Covid in routine day three testing.
The third person to test positive had arrived here two days ago from the United States. They were tested positive on arrival. They were now in quarantine in Christchurch.
There are now 61 active cases in New Zealand.
The ministry said yesterday that 4,106 tests were processed. The seven-day rolling average up to yesterday was 5,342 test.
New Zealanders were today praised for the increase in scanning since last week's community outbreak,
"Since midday yesterday New Zealanders have scanned 692,042 times. The seven-day rolling average number of scans is 1,052,430.
"We thank all New Zealanders for their efforts to scan, scan, scan," said the ministry.
It comes as moves are made to tighten protocols in our managed isolation facilities which have seen movement curtailed after a community outbreak stemming from Auckland's Pullman.
This is followed later in the afternoon with a press conference from director general of Health Dr Ashley Bloomfield and Medsafe group manager Chris James who will reveal the decision-making process to approve the Pfizer vaccine.
With community cases still not surfacing from the latest Northland and Auckland scares, protocols have now been tightened for movement in communal areas in managed isolation facilities.
Across all hotels, returnees now need to make bookings for exercise and smoke breaks, and movement within all 32 facilities has been reduced.
The Pullman Hotel is currently being emptied of guests, while an investigation continues into identifying the source of the outbreak which saw four people staying on the same floor contract Covid in January.
It's believed the likely cause of infection was airborne.
Yesterday the Ministry of Health confirmed five returnees had been infected by a source
within New Zealand managed isolation facilities since the pandemic began.
The infections involve seven events across five facilities.
There had also been five staff infected within the managed isolation facilities in Auckland and Christchurch as of February 1.
But they did not include the 13 international mariners staying in a Christchurch managed isolation facility, who were thought to have contracted Covid-19 overseas.
There are now 69 people with Covid in New Zealand.
There have been no new cases within the community since the two people - a man in his 40s and his preschool daughter - staying in managed isolation at the Pullman Auckland hotel were confirmed to be infected last Wednesday.
The pair from Orewa had finished their 14-day isolation on January 15. Father and daughter were now recovering at the dedicated quarantine facility at Jet Park hotel in South Auckland.
Those cases followed that of another confirmed case in the community, on January 24, of a 56-year-old woman from Northland who had also completed managed isolation at the Pullman facility.
The woman, who contracted the contagious South African variant from another returnee at the central Auckland facility, has since recovered and all of the potential close contacts returned negative tests.
All were found to be linked to a single case at the Pullman Hotel who had been shifted from managed isolation to the Jet Park quarantine facility when she fell ill.
