The couple claim their former PA Gilles De Bonfilhs was “disgruntled” and had been sacked for serious misconduct.
In the lawsuit, De Bonfilhs claims Field “walked around in various stages of undress, shared details about her sex life, questioned him about his sex life and asked him to answer questions and comment on her body”.
“The claims being made by a disgruntled former employee, after he was sacked for serious misconduct, are entirely without substance,” a spokesperson for the pair said in a statement.
“Any proceedings will be strenuously defended. There will be no further comment on the matter as it is in the hands of the lawyers.”
According to their representative, De Bonfilhs only worked with Williams and Field for a short time, before he was let go in January.
The former Take That singer, 41, is named as a defendant in the law suit, but is not accused of sexual harassment.