The California-based law firm, Aiman-Smith & Marcy, said that iGate's head of investor relations Araceli Roiz was pregnant with Murthy's child.
Murthy told the iGate board of his relationship with Roiz only after she informed him that she will be taking legal action against him, Roiz's legal firm Aiman-Smith & Marcy said in a statement.
iGate had earlier this week terminated Murthy's contract for not reporting a relationship with Roiz. Murthy, one of the industry's best-known executives, was forced to quit India's second-biggest software services exporter Infosys in 2002, following a sexual harassment lawsuit, which was settled out of court.
The law firm, which had represented Reka Maximovitch and Jennifer Griffith in the previous sex harassment lawsuits against Murthy, said Roiz remains an employee of iGate and is on medical leave at present.
"When he discovered this (that Roiz was pregnant), Murthy pressured Ms Roiz to have an abortion. When she refused, he told her to leave the company, quietly, to protect his position as CEO," it said in the statement.
Murthy, who had after his sacking stated that he was in relationship with Roiz for "few months" and the sexual harassment case against him was an extortion attempt, could not be immediately reached for comments.
The law firm claimed Murthy began pursuing Roiz shortly after she joined iGate in May 2010 and insinuated himself into her personal life using the pretext of business necessity.
"On behalf of Roiz, we are contemplating next steps, which will certainly include court action against Murthy and iGate," it said adding the Fremont, California-based company was liable for the conduct of its CEO.
While sacking Murthy, iGate had said that an outside probe, which is continuing, had not found any violation of the company's harassment policy.
"We do not believe a full, impartial, investigation can possibly result in this conclusion, but we note that, according to iGate, its investigation is continuing. We hope that iGate will take appropriate responsibility in this matter and that it can be concluded on that basis," the law firm said.
On Murthy's claims that Roiz was engaging in "extortion" by bringing this case against him, the law firm said "Murthy's comments are defamatory and a despicable attempt to 'blame the victim', who only wants to somehow continue her career and support her child."