The leader of a Christchurch mosque targeted in fresh online threats being investigated by police said they are "concerned but not scared".

A menacing selfie of a masked man posing outside Al Noor Mosque, where 42 Muslims were murdered during Friday prayers on March 15, 2019, was spotted online and reported to police.

And police have confirmed they're investigating three separate reports of threats over the past fortnight.

Federation of Islamic Associations chair Abdur Razzaq is responsible for one of the reports after he drew police attention to an offensive image on an online forum.

Razzaq was pleased with the quick response from police, saying that within eight minutes they had reacted.

And within 14 minutes, police officers were already at Al Noor Mosque getting more details.

A police presence was visible at the Al Noor Mosque in the lead up to the March 15 anniversary earlier this year. (Photo / George Heard)

The New Zealand Security Intelligence Service (NZSIS) is also understood to have been called in.

Canterbury Metro Area Commander Superintendent Lane Todd says police are taking the reports seriously, saying any form of abuse based on race or religion is considered serious.

Al Noor Masjid Imam Gamal Fouda says the threats only act to unite the community even more.

"We are concerned but not scared," he told the Herald this morning.

Far-right violent groups want to spread fear among New Zealanders [but] we are united and we will stay united.

"This threat pushes us to be more brave and to continue the public debate about hate speech law."

Fouda, who survived the March 15, 2019 mosque shootings which claimed 51 lives, including 42 people at his Deans Ave mosque, is confident that New Zealand has the expertise to get hate speech laws right.

Razzaq says he feels like these types of posts and comments are being normalised.

He says it only took one person to post an Islamophobic comment before they committed the March 15 terrorist attack.

People need to understand hate speech like this leads to hate crime, he says.

Razzaq believes that until New Zealand bands together to say it's not good enough, people will get a free ride to say harmful comments.