An Australian woman who suffered burns along with her sister in an acid attack at a London nightclub has questioned security arrangements at the venue.
Isobella and Prue Fraser, both aged in their 20s, were among a dozen people injured when a male suspect splashed the "noxious substance" into the crowd at Mangle nightclub in Dalston, east London, on Monday night.
Prue, who lives in the UK, said she was pushed over a small barrier when a fight broke out between two groups.
"I felt this pain in my arm, it was just like a pain I'd never felt before," she told ABC television.
"It was like a burn or a cut. I didn't really feel anything splash on my arm, it happened so quickly."
"Everyone was crying, it was horrific," Prue told the Seven Network on Tuesday.
Isobella, a model who was visiting her sister, saw the suspect throw the acid from a bottle directly into the faces of two men.
She suffered chemical burns to her back and arm and said her top was stuck to her skin.
"I couldn't breathe," Isobella told Seven.
"I thought we were getting gassed, I thought it was a terrorist attack."
The pair went outside before an ambulance arrived and, thinking their injuries were not serious, left and tried to sleep.
"We just wanted to get out of there," Prue said.
The burns continued to intensify and they later visited a hospital.
Prue estimated there were about 600 people in the Dalston club.
"The security wasn't that tight, I don't think there were a lot of people being kicked out for bad behaviour," she said.
"I don't know how they've gotten that (the bottle) in. I guess the bag checks weren't that good."
Another witness, who asked not to be named, told Britain's Press Association the club was "very, very packed".
"I thought someone had dropped a cigarette on my foot but it was getting more red and stinging," she said.
The club is co-operating with the investigation into the matter.
Two men in their 20s are in a serious but stable condition in hospital.
"The substance is yet to be identified but it is believed to have been acidic," police said in a statement.
The London Fire Brigade said the substance was identified by a PH paper test as a strong acidic substance.
The sisters' blood tests have not shown anything out of the ordinary but they will revisit doctors on Tuesday afternoon.
The male suspect remains at large.
© AAP 2017