By 2010 about half of all containers arriving at the port will be 9ft 6in high

Transport Minister Charlotte Atkins launched the �30m scheme which runs between Felixstowe port in Suffolk and Nuneaton in Warwickshire on Thursday.

The route allows freight trains to transport 9ft 6in-high containers on standard wagons for the first time.

This enables operators to meet growing demands for the larger size.

'Huge development'

The upgrade involved work at 31 key locations along the route, enabling the bigger boxes to be transported from ports on the east coast to the Midlands, north-west England and Scotland via the West Coast Main Line.

Felixstowe is the UK's largest gateway for freight in containers and currently receives 1.7m freight containers a year, a quarter of which are 9ft 6in high.

By 2010, it is anticipated that 850,000 containers, or half of all those landing at the port, will be 9ft 6in high.

Speaking at the launch Ms Atkins said: "I am delighted to see the completion of this project as it is a huge development for UK rail freight and a boost for the economy as a whole.

"The execution of the upgrade has been a real success - it's extremely encouraging to see that it has been carried out both ahead of time and under budget."

Strategic Rail Authority chairman David Quarmby said: "One of the UK's premier rail freight corridors now has the infrastructure it needs to fully exploit the growing market for these bigger boxes, which allow more goods to be carried by rail.

"This is not only good news for customers and freight operators, but a good deal for our nation's economy and environment."