NEW trains planned for the East Coast Mainline next year are failing to work properly north of York, it has emerged.

The Azuma trains, which are being built by Hitachi in Newton Aycliffe, County Durham, do not work properly with ageing trackside equipment on the network.

While Network Rail said it was Hitachi's responsibility to show the trains could run safely on the line, it said it was looking at the trackside infrastructure to make improvements.

In tests, the combined electric and diesel Azuma trains could only run on diesel north of York due to the issue, which means they run much slower than their maximum speed.

The Azuma trains are currently being tested on the East Coast main line and were due to be introduced into service in December this year. Network Rail said it could not confirm whether that date will be delayed.

A spokesman for Hitachi said: “There are a number of 30-year old signalling systems on the East Coast main line which require modifying to operate with modern electric trains – which has been confirmed by an independent report.

"Network Rail is planning to carry out this modification work before the Azuma trains enter into passenger service. This is the same issue encountered 15 years ago when the Pendolino was introduced on the West Coast Mainline.

“Whilst testing started over 12 months ago, this issue has been identified by Network Rail only recently during multi-train testing. Hitachi is working hard to support Network Rail to overcome this interface issue.”

Network Rail said electro-magnetic emissions from the Azumas were interfering with existing safety critical systems and it was aiming to find 'a practical solution to ensure passengers benefit from the new trains'.

"We are committed to delivering improved passenger services and the new trains continue to be tested on the East Coast Main Line," a spokeswoman said.

Shadow Transport Secretary Andy McDonald described the situation as 'chaos'.

"The procurement of the new East Coast Intercity Express Programme (IEP) trains has been, yet another incompetently managed Department for Transport project which has cost taxpayers hundreds of millions of pounds. Once again, the Secretary of State has failed to ensure that the different parts of the rail industry work together to deliver new infrastructure and services."

Transport secretary Chris Grayling admitted there were 'teething problems' with the rollout.

Sedgefield MP Phil Wilson said the problem has been known about for between ten and 15 years.

He said: "The problem was first identified on the West coast and it has never been resolved. The trains have been made to Government's own specifications so the problem not lie with Hitachi.

"These trains are what the people in the region want but clearly we haven't got the infrastructure that the Government claims that we have.

"I can assure people that I will be writing to Chris Grayling to discover how long it will take to address the issue."