Two of Britain's most successful architects have declined invitations to design the country's new generation of nuclear power stations.

Practices headed by Norman Foster and Richard Rogers refused to work with French energy company EDF, which is currently drawing up a framework to design stations, reported Building.

Rogers Stirk Harbour + Partners turned down an offer to tender on ethical grounds. Andrew Morris, the practice's commercial director told Building: 'We have a fairly strict constitution set up by Richard [Rogers] which prohibits work on military schemes and power stations.'

A spokesman for Foster + Partners cited business reasons for declining to participate. Other firms approached by EDF are thought to include SMC Alsop and Building Design Partnership.

The news came as EDF continued negotiations to buy UK nuclear power company British Energy. It is rumoured that a £12bn bid turned down in July has now been increased.