TOKYO (AP) _ Telecommunications giants AT&T Corp. and British Telecommunications PLC have agreed to take a combined 30 percent stake in Japan Telecom Co., a report said today.

Under the deal, AT&T and BT will each hold a 15 percent stake in Japan Telecom, Japan's third-largest long-distance telephone carrier, and gain a seat on the company's board of directors, the Nihon Keizai financial daily said.

The total size of their combined investment could be as much as $1.5 billion.

The three firms are reportedly planning a broad alliance in which AT&T and BT will integrate most of their Japanese operations with Japan Telecom's units.

The three companies will offer Internet and other data communication services to multinational corporations and will also cooperate in neighboring Asian telecommunications markets, the Nihon Keizai said.

AT&T is the largest long distance and international carrier in the United States, while BT is Britain's biggest telecommunications company. Japan Telecom is an affiliate of East Japan Railway Co.