Migrants who were brought to Malta by the AFM on Monday have been placed in isolation after 65 tested positive for COVID-19.
The Health Ministry said 85 of the group of 94 migrants had been tested so far, of whom 65 were positive.
"As per usual procedure, migrants arriving by boat are immediately quarantined for 14 days and tested. The migrants who are positive will continue to be isolated at the Ħal Far Initial Reception Centre and the rest will remain in quarantine and followed up," the ministry said.
Swab tests from another nine migrants are pending and will be issued on Tuesday night.
The Ħal Far Initial Reception Centre, which until last year served as a run-down dormitory for migrants known as China House, was converted into a medical facility during the height of the COVID-19 crisis, capable of housing up to 150 people.
The group of 94 were brought to Malta on Monday evening after the boat they were crammed onto started taking in water.
They are understood to be from Eritrea, Morocco and Sudan.
AFM personnel who interacted with the group wore full personal protective equipment throughout, a Home Affairs Ministry spokesperson said, adding that the chances that any officer was infected is "minimal".
"However, the case is now in the hands of health authorities and they will decide on the best course of action," the spokesperson said.
'Lower chances of community transmission'
The cluster is the biggest to ever break out in Malta, although sources within the health sector told Times of Malta that it would be relatively easy to manage.
"This group arrived in Malta together and were in contact with very few other people before they were tested," they said.
"Although it is a large cluster, the chances of further transmission are far lower than among cases within the general population".
The previously record one-day total of new cases - not in a single cluster - was 52, on April 7.
That same month, the Ħal Far open centre where many asylum seekers are housed was closed off and the residents quarantined, after a number of positive cases were detected among residents.
Malta had shut its ports to asylum seekers at the height of the COVID-19 outbreak in spring, citing the pandemic as a reason.
It is the second time authorities have detected a COVID-19 case among rescued migrants, after Only July 18, a migrant who had been brought to Malta one day prior also tested positive for the virus.