Virgin Media will roll out 50Mbps network services later this year after a successful trial with Nortel and Juniper.

The 'North-South' trial, which the companies claim is the first of its kind in the UK, carried 40Gbps traffic on the Virgin network over a 350km stretch between London and Manchester.

The test used Juniper's routers and Nortel's Adaptive Optical Engine, which the firm claims can wring 40Gbps and 100Gbps speeds out of existing 10Gbps networks.

"Our aim for this trial was to ensure that we continue to meet the growing capacity needs of the high-speed services we deliver," said Daniel Hennessy, director of technical architecture at Virgin Media, in a statement.

"Our optical network will provide a solid foundation for growth as it takes advantage of technology designed to avoid electrical regeneration and, where possible, reduce the incremental cost of scaling transport capacity."

Virgin has not set a date for the new high-speed services, but said in its first-quarter financial results that they would be introduced later this year offering four tiers of service with network speeds of 2Mbps, 10Mbps, 20Mbps and 50Mbps.

Virgin's results show a mixed bag. Customer churn is down to 1.2 per cent, the lowest since 2004, and broadband customers are being added at between 80,000 and 90,000 a quarter.

Virgin Media now has 3.5 million domestic broadband subscribers in the UK. But average revenue per user for cable services is down to £41.91 from £42.75 last year, which has depressed revenue by two per cent to just over £1bn.

Operating loss is down to £5m from £15m this time last year, but the saving is dwarfed by the group's long-term debt of nearly £6bn.