RAIL infrastructure group Network Rail yesterday announced half-year pre-tax losses had mushroomed to £233m from £3m.

The not-for-profit company said the bottom line loss in the period between April 1 and September 30 came as it made an operating loss of £95m against profits of £121m last time.

But it said the performance of the rail network, which it took over from failed privatised group Railtrack last year, had improved, with 82.4 per cent of trains running on time compared with 81.8 per cent in the first half of last year.

That came despite significant delays caused by the heat-related speed restrictions imposed on the network this summer and the power blackout in parts of the UK in August, the company said.

It added that it was increasing investment in rail infrastructure, with maintenance spending increasing to £685m from £583m last time.