The European Central Bank has reacted angrily to an advertisement placed in yesterday's Guardian by Conservative leader Michael Howard, which called on public sector workers to provide evidence of waste and bureaucracy.

The ad claims that, "according to the European Central Bank, £70 billion a year is being lost through waste", an estimate from a report by three independent economists and one which was later denied by a Bank spokesman.

"It is three times wrong," he said. "The figures are not in the report and it is not the ECB that says that. The view in the paper is that of the authors and certainly not that of the ECB."