'£20 million a week' loss-maker on the brink...BT and AT&T are on the verge of disbanding their joint venture Concert, according to reports over the weekend. If the two telecommunications giants do go their separate ways it will mark the end of their co-branded and co-hosted long distance telephony venture aimed at big business. It would also mark the latest step in BT chairman Sir Christopher Bland's company restructure. Sir Christopher and his counterpart, AT&T chairman Michael Armstrong, are understood to have met on Friday to discuss the future of the venture. According to the Sunday Times, the two men had initially been discussing a possible three-way merger between Concert, AT&T Business Services and BT Ignite. While this is the preferred solution, the paper claimed, both are prepared to take the more pragmatic route to end a relationship that is said to be losing up to £20m a week. The break-up is unlikely to be clean as both sides will be keen to hold on to customers each regard as among their most lucrative. Since he replaced Sir Iain Vallance earlier this year, Sir Christopher has set about cutting BT's mounting debt. Within a week of taking over he had negotiated the sale of BT's share in Japan Telecom to archrival Vodafone. He has also instigated talks with T-Mobile, the Deutsche Telekom subsidiary, in an effort to share infrastructure costs for forthcoming 3G services in Britain and Germany. Now this latest move would come as little surprise to industry watchers. Concert has long been seen as an expensive luxury for two company's eagerly looking at cost cutting measures. Sir Christopher has gone on record describing the loss-making venture as "unsustainable".