Salvini's proposal caused outrage among members of the opposition and Jewish organizations, who drew parallels with race laws approved during the regime of Benito Mussolini.
"I am having the Interior Ministry prepare a dossier on the Roma situation in Italy," Salvini told TeleLombardia, a northern Italian TV station, on Monday.
"We will try to understand how we can intervene, doing what years ago was called the census, we can now call it the registry or the situation, a picture -- to understand what we are dealing with," he added.
"The Italian Roma, unfortunately, you have to keep in Italy," he said, referring to Roma with Italian citizenship.
'Memories of racist laws'
Ethno-racial statistics have not been permitted in Italy ever since the overthrow of Mussolini's Fascist regime, which introduced legislation in 1938 discriminating against Jewish and Roma minorities.
: "Yesterday refugees, today Roma, tomorrow guns for all. How hard it is to be bad."
Ieri i rifugiati, oggi i Rom, domani le pistole per tutti. Quanto è faticoso essere cattivo— Paolo Gentiloni (@PaoloGentiloni) June 18, 2018
Similarly, the Union of Italian Jewish communities released a statement saying: "The announcement by the Minister of the Interior Matteo Salvini of a possible specific census of the Roma population in Italy is worrying and awakens memories of racist laws and measures of just 80 years ago and sadly ever more forgotten."
But Salvini's allies in the governing coalition also slammed the proposal. The Five Star Movement's Luigi Di Maio, who is deputy prime minister and minister for economic development, labor and social policies, called a Roma census "unconstitutional," according to La Repubblica.
Salvini's Facebook post also contradicted his own press representative, who had denied that a full census of Roma people would take place. "Roma people: Salvini, no cataloging. We must protect Roma children," Iva Garibaldi told CNN in a text message.
"It is not our intention to catalog or take digital fingerprints of anyone. Our objective is to patrol the situation of the Roma camps. We intend to protect thousands of children who are not allowed to attend schools regularly because they prefer to introduce them to delinquency. We also want to control how the millions of euro from EU funds are spent."
It is estimated that 180,000 Roma people live in Italy and 50% of them have Italian citizenship, according to the 2015 annual report of the Italian nonprofit organization Association July 21, which campaigns for the rights of Roma and Sinti people in Italy.
Salvini also said he would seek agreements with Romania, Albania and Tunisia to expel foreign detainees. These nations, he said, "are among the principal countries of delinquents in jail."