Naples police recently carried out a series of raids

The man, who was detained in Barcelona, faces extradition to his native Italy, where he is due to serve a 24-year prison sentence for drug-trafficking.

The arrest follows a series of recent raids by Naples police resulting in 29 people being detained for suspected involvement in organised crime.

Violence between rival Naples gangs has left about 100 dead in the past year.

Spanish police identified the man, arrested in Barcelona at Italy's request, as Humberto A, aged 49.

Italian and Spanish police tracked him down after he made calls from several public telephones in the city, police said.

Silence broken

Seven of the alleged Mafia-members detained in Italy were arrested in connection with the killing of 49-year-old Carmela Attricea, reportedly the relative of an alleged member of one of the local gangs fighting for supremacy.

If citizens do their part, the Camorra is not invincible Giuseppe Pisanu, Italian Interior Minister

Reports say police were able to catch the suspects after local people broke the wall of silence that usually surrounds the killings.

Italian Interior Minister Giuseppe Pisanu praised the unusual level of local co-operation with the authorities following the woman's murder on Saturday.

"Thanks to the precious help of two eyewitnesses, we arrested seven suspects in the death of Carmela Attrice within a few hours," he said.