Adele halted a concert in Sydney after a fan suffered a cardiac arrest mid-way through her performance.

The singer became concerned after medics arrived to attend to a woman in the audience.

In footage from the concert at the ANZ Stadium on Friday night, the 28-year-old can be heard asking the band to stop and saying: "I'm sorry, there's fireworks in this one and I don't want to scare them.

"Is it OK to carry on? OK. Sorry, someone got hurt. I'm really sorry."

The 47-year-old woman was taken to hospital and confirmed to have suffered a cardiac arrest.

Concertgoer Daniel Lowe told Australia's 9 News: "Security staff were trying to rouse her because they assumed she fainted.

"It took a full song for the actual on-site medics to respond.

"They then started performing chest compressions for a good 15 to 20 minutes until ambulance officers arrived with proper equipment."

Mr Lowe added that Adele was "visibly upset for the rest of the show".

"She wasn't as perky and smiley as she was as before," he said.

Another fan, Meg Rylance, told Daily Mail Australia that she was sitting near the woman who collapsed.

She said: "(Adele) stopped the concert.

"She actually seemed really tearful."