A Tesco employee received a final warning after she told a lesbian couple at its Surrey Quays branch that gay people "should not have babies and will die alone".
The homophobic rant came on 3 January when the cashier, who has been named only as Maggie, made comments about a lesbian couple, one of whom was pregnant, after they left the store.
After the couple left, Maggie told the next customers, Natalie Rivans and Helen Embleton (who by coincidence were also lesbians) that "they're gay" and "it's wrong".
She continued, saying "gay people shouldn't have babies", before Rivans confronted her over the remarks, reported the Evening Standard.
However, the cashier continued her tirade, saying it was a "free country so I can say what I like" before adding "all gay people should die alone".
Tesco told Rivans, who complained about the incident, that the cashier would face disciplinary action, and received a call on 9 January to confirm Maggie had been given a final warning after admitting to making the remarks.
A spokesman for Tesco said: "Following inappropriate comments in store by one of our colleagues we have apologised to the customers involved and an internal investigation is now underway.
"Any remarks or actions from our colleagues which are not in line with these beliefs are not acceptable and will not tolerated."