Ms Allwood, who miscarried all the babies, claims in a writ issued to the High Court that Britain's most renowned publicist "failed to exercise due care, skill and diligence" during the handling of her case.
The writ also claims Mr Clifford took money from a national newspaper for divulging Miss Allwood and her boyfriend Paul Hudson's address after the couple had gone in to hiding.
Last night Ms Allwood was unavailable for comment but Mr Clifford said he was saddened by her decision. "It's beyond me. There's no justification for this action whatsoever. As you can appreciate the situation was highly emotional and it all happened some nine months ago," he said.
"I am very happy with the part I played in protecting them and making sure they got the right medical expertise. I think I faced enough criticism for taking on this case at the time and that's why I will fight this case all the way."Reuse content