ATHENS (Reuters) - Greece will tighten border controls to prevent the spread of coronavirus, focusing on island routes used by migrants to enter the country, Prime Minister Kyriakos Mitsotakis said on Thursday.

His comments came as Greece reported two new cases of coronavirus, bringing its total of confirmed cases to three - two in the northern city of Thessaloniki and one in Athens.

The Athens case involved a Piraeus Bank employee who had traveled to Italy, a bank official said. The bank asked all staff who worked on the same floor as the infected employee to work from home for the next 14 days.

Greece is a gateway for refugees and asylum seekers fleeing war and poverty in the Middle East and beyond, with more than one million having passed through the country in 2015 and 2016.

Thousands of migrants are stuck in overcrowded refugee camps in conditions aid organizations say are appalling and which the government itself has described as a “ticking health bomb”.

“Our islands are already overburdened with public health issues and they must be doubly protected,” Mitsotakis, whose administration has taken a tough stance on migration, told a cabinet meeting.

Mitsotakis said he had invoked a European Union directive allowing member states to elevate border security if public health was at risk.

“Putting it simply, we will do whatever it takes to prevent the appearance of the virus - particularly there,” he said, referring to the islands.

The United Nations refugee agency UNHCR says there are more than 40,000 refugees and asylum seekers on Greek islands. Many have waited for months for their applications to be processed.

Governments ramped up measures on Thursday to battle a looming pandemic of the coronavirus as the number of new infections outside China for the first time outpaced new cases in the country where the outbreak began.

After a decade-long debt crisis, concern is growing over the potential impact of the virus on Greece’s economy, which relies heavily on tourism.

Bookings have been affected but not to a great extent, government officials said, calling for calm.

An official at the Bank of Greece told Reuters the central bank was so far sticking to its projections for an economic expansion of 2.4% to 2.5% this year.