Italian police have found more than 100 immigrants, including 24 Afghan children, living in the sewer system beneath railway stations in Rome.
The children range in age from 10 to 15 years and are now being looked after by the city's social services.
They were found when the railway police followed up reports of children living near the city's stations.
The police say they do not speak Italian and broke into the sewers by removing manhole covers.
The charity Save the Children Italy says that more than 1,000 unaccompanied children arrived in Rome last year from various countries in Asia, Africa and Latin America.
Railway police had been following up reports that groups of homeless immigrants were living in unhygienic conditions in and around Rome's three main railway stations.
Police said the Afghan children appeared to have arrived in the Italian capital as stowaways on board trailer trucks arriving from Turkey and Greece.
Some children were sleeping at night in sewers under the railway station to shelter from the cold, police said.
The number of foreign minors arriving in Italy has risen substantially over the past five years, according to children's charities.
Roman police also recently discovered groups of illegal immigrants from Bangladesh and China living crammed 20 or more to a room.
As fast as the authorities find them proper accommodation, their places are taken by new arrivals, the BBC's David Willey reports from the Italian capital.