Gerhard Schröder, the German chancellor, hammered a new nail into the coffin of his ruling alliance of Social Democrats and Greens yesterday when he called for a relaxation of legislation governing stem cell research.

The rules, among the most restrictive in the world, were enacted in 2002 by Mr Schröder's government on the insistence of the Greens, despite criticism from business and scientists. The law, also backed by Christian conservatives at the time, bans the harvesting of stem cells from human embryos within Germany as well as their import unless these stem from cultures predating the legislation.