"We need limited extensions until we are able to work with sensible alternative technologies in an economical and environmentally friendly manner," Karl-Theodor zu Guttenberg told the Sueddeutsche Zeitung daily in an interview.

"That includes the possibility of equipping existing nuclear power stations with state-of-the-art technology in order to make them even safer and more efficient," the conservative minister said.

"But I see no need to build new nuclear reactors."

Asked if he were in favour of reversing the decision to abandon nuclear, zu Guttenberg said: "If we can manage to put in place quickly enough alternatives that make economic sense, no."

Germany decided in 2000 under former premier Gerhard Schroeder's Social Democrats (SPD) and the Greens -- when current Chancellor Angela Merkel's conservatives were in opposition -- to mothball its 17 reactors by about 2020.

The CDU/CSU conservative bloc's has been calling for some time for a re-think, but zu Guttenberg is the first conservative minister to rule out building new plants.

His comments are significant because they come less than four months before general elections in September.

At the election Merkel has the very real possibility to be able to dump as coalition partners the fellow architects of the nuclear phase-out, the centre-left SPD.

High oil prices in 2008, worries about the reliability of supplies from the Middle East and Russia and efforts to reduce Germany's greenhouse gas emissions have made a return to nuclear, as Italy is doing, less unpalatable.

German firms like Siemens, EON and RWE have highly active in tapping into the renewed interest in nuclear being seen worldwide, with over 30 reactors currently in construction, according to lobby group Deutsche Atomforum.

But polls show that a majority of Germans still remain opposed to nuclear power and believe the technology remains highly dangerous because of potential accidents and terrorist attacks.

Shipments of nuclear waste from France and other countries to the Gorleben storage site in northern Germany regularly spark angry protests by thousands of people.

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