It may be an unseemly example of a private row being played out in public, but the Battle of Liz Hurley's Bulge looks as if it will run and run.

The spat between the actress and her former boyfriend, multimillionaire Stephen Bing, took a new twist yesterday as she reacted to his claim that he may not be the father of her forthcoming child.

This week, a month after Mr Bing - dubbed Bing Laden by Ms Hurley's supporters - ended their relationship on learning she was pregnant, he issued a euphemistic statement suggesting she had slept around during their 18-month relationship and that his paternity was in doubt.

In a phrase likely to be recycled by family lawyers for years to come, he said: "Ms Hurley and I were not in an exclusive relationship when she became pregnant. It is her choice to be a single mother. The insinuation that I would not care about the wellbeing of another human being has been very hurtful. If I am indeed the father, I will be an involved and responsible parent."

Ms Hurley said the lack of exclusivity was news to her. "I am deeply distraught by Stephen Bing publicly declaring that he hadn't been in an 'exclusive relationship' with me. This was the first I had heard of this, and the implications are very painful - especially as I am shortly to give birth to his child.

"I loved Stephen enormously during the 18 months we were together ... we were still very much happy together when I discovered I was pregnant. I was loyal and faithful to [him] throughout this time, as he assured me he was to me."

Matters have been further clouded by the emergence of Brenda Swanson, 39, an actress and former gymnast, who said at the weekend that she and Mr Bing had been lovers since late summer.

Ms Hurley was pictured during the same period in a clinch with a man named as Mark Reynolds, in New York, and with Tim Jefferies, the Green Shield stamp heir. Her former lover, actor Hugh Grant, had been providing moral support, friends said.

Mr Bing is understood to want a DNA test from the baby. If the father, he will almost certainly be involved financially; by Californian law a Hurley junior would be entitled to a big chunk of the £400m fortune that Mr Bing is set to inherit from his property mogul father.