A passionate wedding haka that moved a New Zealand bride to tears is making everyone else cry too after being watched more than 13 million times.

Video of the Maori dance at the wedding of Aaliyah and Benjamin Armstrong is being widely shared on social media.

Armstrong, 21, told the BBC she was "blown away" by the performance.

She said the haka was a sign of respect from her husband's best man and family not, as some have commented online, an attempt to intimidate him.

"They are quite strong, the men in their family," she said.

A haka – with its shouting, body-slapping and exaggerated facial expressions – is used in traditional Maori culture as a war cry to intimidate the enemy, but also to welcome special guests and at celebrations.

The video was filmed at the couple's wedding reception in Auckland last week.

In it, they watch with emotion as the groomsmen and guests surprise them with a heartfelt performance of the traditional dance, before joining in themselves.

"I wasn't planning on jumping in until one bridesmaid did. I felt the need to show love and respect back," said Armstrong. "I was really blown away."

Women do not normally perform the haka in Maori culture, but she said they can do at weddings.

The nearly three minute video ends with the couple emotionally embracing the performers.

'Moved me to tears'

The haka was organised by the 23-year-old groom's best man and was led by his older brother. It was filmed by her cousin's production company.

"Ben is a Maori, he is probably more Maori than I am," Armstrong said.

"Because he has fair skin, some people have been saying on social media that 'he'd better not hurt the bride', but they're actually his family."

The couple, who live in Auckland, posted the video for friends and its popularity has taken them by surprise.

"We didn't think it would shoot off, but yesterday afternoon I left my phone alone for about five minutes and I had so many notifications," Armstrong said.

Comments on social media have focused on the strong emotions that the video arouses.

"Yes, this moved me to tears," said user Hind Makki in a typical Twitter post.