The Avis Budget group has moved to derail an agreed takeover of Dollar Thrifty by rival Hertz by making a higher counter bid.

Hertz agreed a $1.17 billion deal for smaller company Dollar Thifty three months ago.

But Avis Budget has now sought to outbid Hertz with an offer valued at $1.33 billion.

Avis Budget group chairman and CEO Ronald Nelson wrote to Dollar Thifty’s top executives saying: “We are prepared to put forward an offer today for Dollar Thrifty that clearly constitutes a superior proposal under that [Hertz] merger agreement.”

He added: “We are prepared to enter into a merger agreement that contains substantially the same terms as the Hertz merger agreement, but which includes removing the matching rights, eliminating the break-up fees, and increasing the commitment to secure antitrust approvals.

“In short, we believe that the higher purchase price we are offering, combined with the terms of our proposed merger agreement, makes our offer a superior one from the perspective of Dollar Thrifty and its shareholders.”