Italy Boat Migrant Tuberculosis navy
Migrants sit on the deck of Italian Navy Ship GrecaleTullio M. Puglia/Getty Images

The Italian navy said that eight officers involved in rescue operations of migrant boats in the Mediterranean have tested positive for tuberculosis, sparking right-wing parties' calls for a tougher approach to immigration.

The eight do not have any symptoms of the disease but a routine check revealed that they have been exposed to the bacterium responsible for the potentially deadly lung infection, the navy chief said.

"They are not sick or infected and show no symptoms of the disease but tested positive [to it]," said Admiral Giuseppe De Giorgi. "Additional checks are to be carried out."

De Giorgi said that the percentage of Navy officers who recently tested positive to tuberculosis was lower than the national average and in most cases no medical treatment was needed, as the body's immune system prevented the bacteria from causing sickness.

The news was however seized upon by nationalist parties as evidence that the growing influx of migrants coming ashore represents a health as well as a security threat.

"When the Northern League warned that illegal immigrants would bring diseases and death the right-minded cried scandal; now we have been proven right," said Northern League lawmaker Roberto Caon.

The navy officers who tested positive were involved in a large aid and rescue operation, called Mare Nostrum (Latin for Our Sea), that was launched by the government in October last year to deal with the tens of thousands of migrants trying to reach the Italian coast via sea.

More than 900 navy personnel, five vessels and several aircrafts have been deployed as part of the operation to patrol Italy's southern coast and come to the rescue of rundown migrant boats at risk of sinking.

Hundreds have died in recent years while crossing from northern Africa and the Italian Navy say they have saved more than 20,000 lives since Mare Nostrum was launched.

Critics of the operation, which costs the cash-strapped Italian government €9m a month, however claim that it eases human traffickers' job and encourages further immigration.

To avoid arrest, traffickers often allow overcrowded boats to run adrift miles from the shores of Italy's southernmost Lampedusa Island, counting on the navy to rescue them.

"The government is using the navy as a taxi for illegal migrants," said Maurizio Gasparri, a former minister and a lawmaker with Silvio Berlusconi's Forza Italia party. "What are they waiting for to halt Mare Nostrum? That our soldiers die of tuberculosis?"

The government has accused the European Union of leaving Italy alone in addressing the migration problem.

"The Mediterranean is not an Italian border but a European border," Interior Minister Angelino Alfano said last month.

Some 50,000 boat migrants have reached Italy this year and the number of arrivals in on track to exceed the yearly record of 62,000 set in 2011 during the Arab Spring uprisings.