Auckland mum of two, Lucy Brown, has died after sustaining a head injury during a sparring match.

An Auckland boxer has died days after receiving a head injury during a routine sparring session.

Lucy Brown, 31, died on August 22.

The mother of two was flown to Auckland City Hospital in a critical condition, after she collapsed after routine sparring at Wellsford Boxing Sport & Fitness Club at Centennial Park on August 18.

Facebook Brown was also a cancer survivor, a silver medallist in boxing and a weight-loss success story.

Auckland City Police detective senior sergeant Lloyd Schmid said the woman had been on life support for a number of days and died on Wednesday morning at 7.45am.

"Police are not in a position to release her name at this stage and the matter has been referred to the coroner," he said.

He said, she was airlifted to Auckland City Hospital after feeling unwell and was subsequently put on life support.

Amy Baker Brown was training at Centennial Park in Wellsford when she collapsed after a sparring session.

"Unfortunately there have been a number of conflicting reports in the media regarding when she died and this has not been helpful."

Friends and family have been rallying around, sharing thoughts and prayers for Brown and her family since her injury.

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Auckland Westpac Rescue Helicopter The 31- year-old was flown to Auckland City Hospital.

Tributes have been posted online about Brown.

"Today the world is a darker place. One of the brightest souls has been reclaimed," her cousin Cassie Barton wrote.

"I am heart broken to say that our beautiful Lucy has lost her fight. She was the true definition of a warrior. She fought as hard as she could but she has returned to God.

Facebook Friends and family shared their prayers and thoughts for Brown.

"You are at peace now my girl, you rest. We will always love you, and you will live on through all of us.

"Sending all my love and strength to your family, babe. Fly high."

Tim Griffin from Townsville, Australia, where Brown previously lived, offered his condolences to the family: "We choose to remember Lucy as someone who lived her life to the maximum, but always had time to love and support everyone else as well.

Facebook "One of the brightest souls has been reclaimed," friend Cassie Barton wrote in Brown's memory.

"We are super proud of your achievements and you will be very sadly missed by all."

Ebony Brown-Parker said Brown had "gone way too soon".

"You put up one last good fight, Lucy, but unfortunately heaven needed another angel."

"Rest easy you beautiful soul, you are loved and will be missed by so many."

According to Australian paper, Townsville Bulletin, Brown was diagnosed with stage three cervical cancer in 2011 and survived.

After her cancer battle, she enrolled at a boxing gym to get fit, which saw her halve her weight from 120 kilograms (kg) to 60kg.

She started boxing seriously in 2014, as part of training for a cancer charity boxing match, and went on to compete at the Golden Gloves tournament in Australia, where she won a silver medal.

Barton set up a Go Fund Me page to assist the family with costs.