TOKYO, Japan, April 27 -- AT&T Corp. and British Telecommunications PLC (BT) have agreed to purchase a combined 30 percent stake in Japan Telecom Co., a share valued at $1.84 billion. The US and British telecoms will each hold a 15 percent stake in the Japanese company, the third-largest long-distance and international carrier in Japan. BT is reportedly paying $1 billion and contributing assets worth $257 million, while AT&T is to pay $209 million in cash and contribute $435 in assets.The three companies plan a broad alliance in which most of the Japanese operations of BT and AT&T will be integrated into Japan Telecom, which will also host executives from both stakeholders. BT and AT&T will jointly manage the stake through a holding company. This announced alliance follows last week's $82 billion deal involving Deutsche Telekom AG and Telecom Italia SpA, as well as AT&T's surprise $58 billion bid for cable company MediaOne Group.