The government is considering constructing a new high speed railway line from London to Edinburgh.

Transport secretary Alistair Darling has asked his officials to study the cost and benefits of building a 186mph North-South line.

Speaking at a rail industry conference on Thursday, Darling said: "We need to look ahead at how demand for rail might develop over the next ten to twenty years.

"That means looking at additional capacity, including the possibility of high-speed services to the North and South."

He added: "A lot more work needs to be done on the route and costings for a high-speed line. We need to consider whether it is better to spend money on improving conventional lines or building new ones."