The Prison Service confirmed the disciplinary action took place last month against the pair who work at the 500-inmate Holloway jail in north London.

One has already resigned and the other is being investigated, a spokesman said.

"A third member of staff is under investigation for allegations of inappropriate behaviour towards prisoners but has not been suspended," he added.

Rat infested

It is understood that the allegations were of sexual activity with prisoners.

The incident is the latest in a series of crises to hit the women's jail, where Maxine Carr is awaiting trial in connection with the murders of the Cambridgeshire 10-year-olds Holly Wells and Jessica Chapman.

In 2002, nine female warders were disciplined over allegations of bullying and sexual harassment of colleagues.

Former chief inspector of prisons Sir David Ramsbotham walked out of Holloway in 1995 claiming it was filthy and infested with rats.