German Economy Minister Philipp Roesler stepped up demands for extra cuts to subsidies for wind and solar power providers, aggravating a clash with his Environment Ministry Cabinet colleague over the nation's energy overhaul.

Roesler, who leads Chancellor Angela Merkel's Free Democratic junior coalition partner, wants to go beyond Environment Minister Peter Altmaier's proposals to reform clean-energy support laws, a paper obtained by Bloomberg News shows. The document said that renewable-energy providers should carry more market risk and so curb the cost to the state of Germany's transition from atomic power. It didn't give specific numbers for subsidy cuts.