Italy's far-right Interior Minister Matteo Salvini has said "Islamic extremism" is the only threat to the country in the wake of deadly attacks on two New Zealand mosques.

Italy's far-right Interior Minister Matteo Salvini has said "Islamic extremism" is the only threat to the country in the wake of deadly attacks on two New Zealand mosques that killed at least 50 people.

Salvini made that comments on Friday at press conference, local news website Fanpage reported.

"The only extremism that deserves attention is Islamic," Salvini said, adding that Italian "far-right and left-wing fringes" were under control.

Salvini is frequently accused of stoking racial tensions with anti-immigrant diatribes and of being Islamaphobic.

His Lega always vigorously opposes the construction of new mosques.

Salvini then condemned the New Zealand attacks and asked for "compassion" for anyone who might blame him for the killings.

"Massacre in #NewZealand, condemnation and utter contempt for the odious murderers, prayers for the innocent victims, compassion for those who say 'it's always Salvini's fault'," the anti-immigrant Lega leader tweeted.

Salvini is also deputy prime minister, along with Luigi Di Maio, after forming a coalition with the Five Star Movement.

Di Maio and Prime Minister Giuseppe Conte earlier condemned the deadly attacks on Christchurch mosques in which at least 49 people died, also voicing condolences for the victims.

Australian officials have described the New Zealand attacker as "an extremist, right-wing, violent terrorist". He published a manifesto before the attacks saying he wanted to attack Muslims.

A number of pictures were posted to a social media account of a semi-automatic weapon covered in the names of historical figures, many of whom were involved in the killing of Muslims.

The names included that of Luca Traini, an Italian jailed for 12 years for carrying out six non-fatal racist shootings in Italy's Macerata in 2018.

Traini's lawyer Gianluca Giulianelli told Italian radio on Friday that although he had not spoken to his client since the New Zealand attacks, "Luca would certainly distance himself from this tragedy... because he has for some time now developed a strong feeling of repentance for what he did."

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