TELECOMS group BT unsettled investors yesterday after a £520m deal revived memories of its last disastrous foray in the US.

The acquisition of Californian company Infonet, which provides companies with internal communication systems, was hailed by BT as a landmark move that would boost its global presence.

But many analysts expressed concern about the plan, which comes only three years after BT lost £1.2bn unwinding its loss-making joint venture with US group AT&T.

Infonet, which has a list of blue-chip customers, including Hewlett-Packard, has operations in 70 countries and about 3,000 cities worldwide. It specialises in linking companies through phone networks and intranet systems.

BT's global services division already offers similar services, but the planned purchase will bolster its presence in North America and Asia Pacific. It will add about 1,800 corporate customers to BT's 10,000 clients in the sector.

The acquisition is subject to shareholder and regulatory approval.

Infonet is owned by a number of telecoms companies, including KDDI of Japan, Dutch group KPN and Spanish firm Telefonica.

Analysts at Barclays Stockbrokers said they were not in favour of the purchase, which they believed could presage other similar deals.

They expressed concerns about Infonet's profitability and said investors were likely to become increasingly nervous that their returns might not be as good as previously hoped.