Three new coronavirus cases were diagnosed overnight, bringing the total to 21 so far.

The new cases were also imported, Public Health Superintendent Charmaine Gauci said on Sunday morning.

The first case was of a 23-year-old male healthcare worker, who arrived from Dublin on 10 March. He developed symptoms four days later and went into quarantine.

This person was on holiday with another person who also tested positive for Covid-19 yesterday. Gauci said contact tracing of people on the same flight and those who may have come in contact with the man is being done.

She said the risk of the man passing on the virus to patients was very low but his work colleagues have been placed in quarantine.

The second case involves a 20-year-old male student who also returned from Dublin on 10 March and developed symptoms two days later. He attended a lecture and so contact tracing of students who may have come in contact with the individual is being carried out.

The third case is of a Portuguese 21-year-old man who works in Malta. He arrived from Madrid on 10 March and developed symptoms three days later. He went into self-quarantine with his girlfriend.

Gauci said the health authorities had so far carried out 722 tests for Covid-19 on people who came from abroad and showed symptoms, and 663 tests on other people who did not go abroad but displayed some sort of symptoms.

She said that two patients had recovered and were now back home in quarantine.

Gauci said the police and public health inspectors had fined three people who were found to have breached the mandatory quarantine.