A Texas judge issued an order preventing banks from taking actions that would “interfere or thwart” the closing of a proposed $19.5 billion buyout of Clear Channel Communications Inc., the company said in a statement today.

The Associated Press reported that the nation’s largest radio station operator filed a lawsuit Wednesday, claming that the six banks that promised to finance the deal were changing the terms of their earlier commitment and putting unreasonable conditions on the loan in an attempt to end the deal. A group of private equity firms, including Bain Capital LLC and Thomas H. Lee Partners LLC, agreed to pay $39.20 per share to take Clear Channel private. The company expected to complete the deal this month.

The judge ruled a temporary restraining order, saying that “irreparable harm” would result if the banks backing the deal were not immediately prevented from interfering with its closing.

The lenders, which include Citigroup Inc., Morgan Stanley and Wachovia Corp., agreed in a deal signed 18 months ago to bear all the risk of changes in the debt market. The buyers claimed they were changing their previous commitments, looking to offer a shorter-term bridge loan rather than long-term financing.