Network rail has apologised for extension to signalling work

The project has already overrun twice. Now the BBC has discovered that it will be after Christmas 2007 before the new signals are up and running.

Trains will be disrupted for most of the year as hand-pulled lever signals are brought back into service.

Network Rail directors have apologised to passengers in the Hampshire city.

Passengers had more than a month without trains at the start of this year before a limited service was introduced at the beginning of February.

Now, around half of South West Trains' services will be allowed to run but Southern trains will continue to rely on a replacement bus service.

I don't think the rail industry has ever seen anything like this Paul Clifton, BBC South transport correspondent

It is likely the line between Fareham, Havant, Petersfield and Chichester will have to close again later this year, although rail chiefs will want to keep it open during the summer tourist season, according to BBC South's transport correspondent Paul Clifton.

He said: "I don't think the rail industry has ever seen anything like this. Some engineers and electricians move into Portsmouth and it takes a year to put right. It's beyond belief."

In a statement, Network Rail blamed the delay on "technical issues" that need resolving with Siemens, the company supplying the new signalling system.

David Pape, route director for Network Rail, said: "We apologise to passengers in the Portsmouth area for disruption and inconvenience this will cause.

"We are disappointed for all our customers, and we will be doing everything we can to finish this work... as soon as possible."

'Robust and reliable'

Christian Roth, managing director of Siemens Transportation Systems also apologised, adding: "Our efforts continue to be focused on the delivery of a robust and reliable railway for the future."

South West Trains (SWT), which is operating a reduced service of two trains an hour to Portsmouth Harbour, said it shared passengers' frustration and was "pressurising Network Rail to complete the work as quickly as it can".

Scheduled engineering work for 15 and 16 March has been cancelled but work on 17 and 18 March will go ahead.

Extra work will be carried out from 31 March to 2 April.