Architect Lord Foster has threatened to sue the German government over a disputed £1.2m repair bill for the £200m Reichstag parliament building in Berlin.

Lord Foster is set to issue a writ to Bundesbaugesellschaft, the Reichstag public-private client, if it does not pay the money. The move follows a letter from Lord Foster to German parliament speaker Wolfgang Thierse urging him to make the Bundesbaugesellschaft pay.

A Bundesbaugesellschaft spokesperson said: “Lord Foster has lifted it [the dispute] into a domain it should not have got into.”

A Foster spokesperson said: “It is a private and confidential matter.”