Croydon's leaders have expressed solidarity with the Muslim community after terrorist attacks on two mosques in New Zealand claimed 49 lives.

Brenton Tarrant, 28, from Australia, appeared to have live-streamed the main terror attack in Christchurch and outlined his anti-immigrant motives in a manifesto posted online.

The Mayor of Croydon, Bernadette Khan, and Council Leader Tony Newman will be attended Croydon mosque later today to express their support for the Muslim community.

In a joint statement they said: "The terror attacks at two mosques in Christchurch, New Zealand, have shocked and saddened us all.

"Our thoughts are with those who lost their lives, their loved ones and those who have been injured.

"As a mark of respect, the town hall flag is flying at half-mast.

"Horrific acts like this aim to create fear, distrust and discord, but we stand together with all our communities and hate will never divide us.

"In Croydon we are proud of our many faiths, cultures and communities and I believe this makes us all richer and stronger.

"Later today we will be attending Croydon Mosque to stand in solidarity with our Muslim community."

Forty-one people were killed at the Masjid Al Noor mosque on Deans Avenue in central Christchurch, seven were killed at the suburban Linwood Masjid Mosque, and one person died at the Christchurch Hospital.

Prime Minister Jacinda Ardern earlier said at least 20 other people had been seriously injured, and described it as "one of New Zealand's darkest days", adding: "What has happened here is an extraordinary and unprecedented act of violence."