Police have charged a 27-year-old man with threatening to kill after he allegedly threatened two Christchurch mosques.

Armed police raided two homes on Thursday after a person made a series of online threats against the Linwood and Al Noor mosques. The mosques were at the centre of the 2019 terror attack.

Police initially arrested two people but released one. 

Canterbury District Commander Superintendent John Price said police take the threats very seriously.

"Any threat made on our community and our people is a threat to our society and will not be tolerated."

"Any message of hate of people wanting to cause harm in our community, they will be held to account."

Police were notified of the threat by a member of the public, Superintendent Price said on Thursday.

"If we're going to keep our society safe from harm, we need everyone to help, and that means we need all members of the public to keep eyes open and to inform us straight away if they have any concerns of people's behaviours or actions."

Price said the man faces the possibility of further charges because it may be seen as a hate crime.

"At this stage, it's a criminal investigation, a threat has been made and we have acted and responded with the appropriate charge."

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Australian terrorist Brenton Tarrant killed 51 people at two mosques on March 15, 2019.

This threat comes ahead of the two year anniversary of the terror attacks at the Al Noor and Linwood mosques. 

Both mosques were searched and cleared by police after the online threats appeared.

The Muslim Association of Canterbury on Thursday thanked police for their support.

"We would like to show our appreciation to New Zealand Police in identifying the threat and acting promptly," spokesperson Abdigani Ali said.

"There is no place for hate rhetoric and hate crimes in our country and every community no matter their race or beliefs should feel a sense of safety and belonging."

The man is due to appear at Christchurch District Court on Friday.