A former London Development Agency (LDA) manager is to sue London mayor Ken Livingstone for libel, according to reports in the Evening Standard.
Brenda Stern was forced from her job after she complained about alleged irregularities in a project run by a friend of Mr Livingstone's equality advisor Lee Jasper.
A complaint of bullying was made against her but in a letter seen by the Standard, LDA chief executive Manny Lewis stated that the claim was investigated and discovered to be unfounded.
However, speaking on BBC Radio 4's Today programme, the mayor described Ms Stern as a "very embittered former member of staff", adding that the agency had tried to get rid of her after complaints she was intimidating other staff members.
Responding to Mr Livingstone's comments, she stated: "What he said about me to six million listeners was completely untrue and I have that in writing from his own LDA chief executive … I will not be intimidated into silence."
Mr Livingstone was first elected to be mayor of London in May 2000.