CBS filed a motion yesterday seeking the dismissal of a lawsuit by Dan Rather, who says that the network violated his contract by giving him too little to do after it forced him off the evening news in 2005 and that its investigation of the news segment about President Bush’s National Guard service was politically biased.

“This lawsuit is a regrettable attempt by plaintiff Dan Rather to remain in the public eye, and to settle old scores and perceived slights, based on an array of far-fetched allegations,” the network said in a 30-page brief filed in State Supreme Court in Manhattan. The papers represented the network’s first response to the suit Mr. Rather filed on Sept. 19.

Referring specifically to Mr. Rather’s assertion that CBS and its senior executives had sought to do the White House’s bidding in commissioning an incomplete investigation of the National Guard segment, the network said: “CBS and its executives are not now, and never have been, out to get Dan Rather.”

Mr. Rather agreed to step down from the “CBS Evening News” in March 2005, a year earlier than he had planned, after the network said it could not authenticate documents that had been used as evidence in the segment about Mr. Bush’s time in the Air National Guard.

In response to arguments that CBS gave Mr. Rather insufficient airtime after he left the “CBS Evening News” — first on the weeknight edition of “60 Minutes” and later on the flagship Sunday edition — the network cited a “pay or play” clause in his contract. “As long as Rather was paid the specified compensation, CBS had no obligation to give him any on-air exposure,” the network said.

In an accompanying statement, the network called Mr. Rather “one of the most important figures in the history of journalism” and said it was “mystified and saddened” by the suit.

A spokesman for Mr. Rather’s lawyers released a statement last night that said: “It is unfortunate that CBS is trying to delay discovery of the facts and a trial of Dan’s claims. We are confident the court will reject these tactics and allow the case to go forward.”