Police have searched a Christchurch property and are speaking to a 19-year-old man in relation to the probe of a reported threat against Al Noor mosque.
Police say he has been charged on an unrelated matter and they are continuing to gather evidence in relation to the threat.
A picture of a person outside the mosque, and threatening commentary, was reportedly sent to thousands of people through an encrypted messaging app on Sunday.
Canterbury District Commander Superintendent John Price said a number of people had been sharing the picture on social media, and it had been referred to the Chief Censor to decide if it should be classified as objectionable material.
"The further sharing of this image is causing significant distress and anxiety for members of our community," he said.
"This type of imagery has no place in Aotearoa New Zealand. It is abhorrent and will not be tolerated."
If the picture is classified as objectionable, anyone who knowingly possesses or shares it can receive a maximum of 14 years' imprisonment.
In the lead-up to the 15 March anniversary, police say they have increased patrols around Al Noor and Linwood mosques and will be maintaining a visible presence in the community.
Price said on behalf of police, he wanted to thank people who alerted them to the threat.
"We ask that you continue to remain vigilant, and encourage you to report anything suspicious or concerning to police immediately," he said.