Firefighters had just put out the first blaze in Ponticelli on the fringes of Naples when a second encampment nearby was set alight, Italy's ANSA news agency said.
Police said the blazes were meant to scare off the Roma, who had abandoned their huts and gone into hiding amid tensions sparked by the attempted kidnapping of an Italian baby by a 16 year-old gypsy girl last Saturday.
Most of them left the encampments in the middle of the night, with roughly 50 remaining in Ponticelli under police protection.
Petrol bombs had already set fire early Tuesday to four huts at the gypsy encampment. No casualties were reported.
On Tuesday evening, hundreds of demonstrators including teenagers armed with sticks had gathered around the camp as a police helicopter hovered overhead, ANSA said.
The Roma attacks near Naples will fan the flames of a wider immigration row developing in Italy, particularly with relation to Romanian immigrants.
Tensions were sparked by the November murder of an Italian woman blamed on a Romanian immigrant of Roma origin.
An estimated 342,200 Romanians are currently living in Italy, though the church charity organisation Caritas puts the figure at 556,000. The number has risen sharply since Romania joined the European Union last year.
The immigrants, and particularly gypsies from Romania, have aroused widespread anger among Italians because they are perceived as the main cause of lack of safety on the streets.
The right swept to victory in April's legislative elections after leading a campaign centred on security issues and largely blaming Romanians for a recent spike in immigrant-related violence.
The new government of Prime Minister Silvio Berlusconi has announced measures to control or expel immigrants, especially the Roma, if they are illegal, found guilty of offences or have no visible means of support.
"The security decree will be adopted by the council of ministers in Naples," Berlusconi told the Senate on Wednesday, describing his bid to associate immigration and crime as "an important twist in security policy."
The decree would make it constitutional for illegal immigrants to face up to four years behind bars before being expelled. It would also make DNA tests obligatory to clamp down on illegal immigrants abusing the system by lying about entering the country to join their families.
New unidentified arrivals could also find themselves stranded in detention centres for up to 18 months, under the new laws.
In Bucharest, Romanian Prime Minister Calin Tariceanu expressed anger that the measures were not directed at other EU citizens, who have freedom of movement within the bloc.
Following telephone talks with new Foreign Minister Franco Frattini, Tariceanu reiterated an offer for Romania to send police and prosecutors to Italy and suggested bilateral talks to defuse a growing immigration row.
Tariceanu has already dispatched Interior Minister Cristian David on an urgent trip to Rome. He is to meet his Italian counterpart Roberto Maroni, a member of the anti-immigration, eurosceptic Northern League on Thursday.