The coalition government had previously pledged to impose a levy on these operators after reversing a planned nuclear phase-out agreed by former chancellor Gerhard Schröder. It intended to use the tax to finance the development of renewable energy.

The plan's weakening comes shortly after an advertisement published by utility firms dismissed the government's proposed taxes on nuclear fuel rods and profits from plants operating beyond 2021. They also criticised a plan to end existing exemptions for energy intensive installations from an eco-tax on fuels and energy.

In an interview published on Saturday, energy commissioner Günther Oettinger – himself a CDU party member – said he supported a tax on profits. At least half of profits should be taxed, he told German newspaper Sueddeutsche Zeitung.

The tax on fuel rods seems far from being rubber-stamped. Last week, environment minister Norbert Röttgen said that the government would not decide on whether to impose it until the end of September. "As long as there is no other proposal on the table, this tax will come," said chancellor Angela Merkel.

The advertisement was initiated by utility firms E.ON, EnBW, RWE and Vattenfall, and supported by the Federation of German Industries (BDI). Germany should use renewables but also stick to nuclear and coal-fired power plants for the time being, they said. Green MPs dismissed the advert as a "crusade against the future".

*Meanwhile, Greenpeace is taking the German ministry of economics to court for keeping a report on the monitoring of energy supply security under wraps. The report was due to be published in July. It will show that Germany will not need to extend the lifespan of nuclear power plants, Greenpeace claims.

Follow-up: Media report on Merkel's nuclear tax plans plus utilities' advert and reaction from Green MPs. See also Greenpeace's press release