Deputy Labour leader Harriet Harman has played down comments by Ed Balls comparing the HS2 project to the Millenium Dome.
Speaking on the BBC's Andrew Marr Show, Ms Harman said Mr Balls did not volunteer the comparison during an interview with a Mail on Sunday journalist.
The shadow chancellor told the newspaper the Dome was a mistake, adding "I think you should learn from your mistakes".
Ms Harman said: "We absolutely support better north-south lines, we are in favour of rail infrastructure for commuters and also for long-distance travellers and freight but not at any cost and what Ed Balls is saying is we have to keep a strong eye on the costs as well as on the benefits."
More top news
Becoming mostly dry this morning then thundery showers developing during the afternoon.
Police have charged a 29-year-old French man with the murder of a British backpacker in Australia.
Rescuers have worked through the night in an attempt to find survivors from Wednesday's devastating earthquake in central Italy.