Network Rail is in charge maintenance

Arriva, the company which runs services in those regions, has written to the UK's rail regulator to complain that the "competency of (independent) contractors used" is too low, the Independent on Sunday reported.

The paper says it has obtained a letter from Arriva, sent as part of the general industry response to new track and station operator Network Rail.

The letter, the Independent on Sunday, said recent examples "include tools left on the line... to be struck by trains; lines blocked with ballast without the contractor realising this; poor repairs leading to repeat failures; and forgetting to fasten the third (electric) rail... following a renewal".

The new not-for-profit firm, which replaced insolvent private company Railtrack, also comes in for criticism from Arriva, which said it was not doing enough to monitor the companies to which it outsources maintenance.

The competence of contractors has been a hot issue since a number of railway accidents have been connected with shoddy workmanship.

One of the companies in the firing line has been Jarvis, which was responsible for the track at Potters Bar station when a train derailed last year.

According to the Independent on Sunday, Network Rail has confirmed that Jarvis holds the maintenance contract on Arriva's Merseyside operations, as well as for 80% of its Northern England franchise.

"We can't deny that some of the incidents have happened," a spokesman told the paper.

"We are working with the contractor to ensure it doesn't happen again."

Following the concerns, Network Rail is taking back maintenance from several contractors, including Balfour Beatty, Serco and others.