A woman has died after she's believed to have taken MDMA at a Lewisham nightclub.

At around 10.53am on Monday, August 28, police were alerted to a 22-year-old woman who had been found seriously unwell at an address in Knights Hill, West Norwood, and admitted to Kings College Hospital.

The woman - a Vietnamese national - was pronounced dead at 11.37am that day.

Police discovered that the woman had taken drugs with some friends, also Vietnamese, at Crystals nightclub in Lewisham on the night of August 27 into August 28.

One other member of the group - a man, aged in his 20s, who is also Vietnamese - was admitted to hospital on August 28. His condition was initially critical but has since improved and he has been discharged from hospital.

Next of kin have been informed. A post-mortem examination will commence on Monday, September 4, at Greenwich Mortuary.

Analysis of a small number of pills seized by police from the address in Knights Hill showed that they contained MDMA and ketamine. Both the deceased and the man now discharged from hospital are believed to have bought and taken these substances while at Crystals nightclub.

The pills are orange and rectangular, with no distinctive markings on them.

At around 5am on Sunday, September 3, a 17-year-old male - also a Vietnamese national - was taken ill at the Electric nightclub in Brixton. He has been taken to hospital where his condition is critical. It is suspected that this male had taken MDMA at the venue.

It is believed several other people became ill at the Electric having taken what they believed to be MDMA, but left the venue without calling emergency service.

Police are warning members of the public - especially those in south London and specifically those in the Vietnamese and South-East Asian community - to take great care in respect of buying and taking MDMA/ecstasy.

Anyone who has taken these substances and feels unwell is advised to seek medical treatment.

Anyone with information relating to the supply of illegal drugs, especially at these venues and within this community, should call Lambeth CID via 101. To remain anonymous call Crimestoppers on 0800 555 111.