A fourth patient was diagnosed with coronavirus in Malta late on Monday.
The government said the latest case involves a foreign national who was on holiday in north Italy in recent days. The patient, who resides in Malta, is in good condition, the government said, though no further details were provided.
"The government appeals for calm and responsibility because there is no reason for alarm or panic."
Prime Minister Robert Abela is expected to hold a news conference at midnight after Italian Prime Minister Giuseppe Conte on Monday evening put the whole country on lockdown and banned gatherings.
The health authorities are expected to give a press briefing on Tuesday morning.
More than 550 tests have been carried out for the virus in Malta, all of which have resulted negative.
A 12-year-old Italian girl became the first coronavirus patient in Malta early on Saturday, followed within hours by her two parents. All three had been on self quarantine after flying in from Rome and have since been receiving care at the Infectious Disease Unit at Mater Dei Hospital. They are said to be doing well.
Monday's case was confirmed on the day Malta stopped flights from northern Italy, which has seen the highest concentration of coronavirus on Europe.
Mater Dei Hospital also announced restrictions on visiting hours and the number of people who may visit patients.
More to follow