The French Treasury has hired seven banks to test international investors' appetite for 50-year euro denominated bonds. The move follows a similar consultation by the UK government and comes amid a clamour of interest from pension funds in long-dated debt.

The four main banks charged with sounding out investor interest are BNP Paribas, Barclays Capital, Deutsche Bank and HSBC-CCF. Credit Suisse First Boston, Ixis and JP Morgan are also involved.