The European Commission has ordered an investigation of a planned alliance between two of the world's largest telecommunications companies : Britain's BT British Telecom and AT&T of the United States.

The decision to open the inquiry follows a complaint by BT's rivals in Britain that the proposed joint venture would have a monopoly of some Transatlantic telephone services, especially those provided to large multinationals.

The EU investigation will last up to four months.

Officials have already indicated they may not have enough evidence of unfair competition to prevent the alliance.