Berlin - The gas dispute between Russia and Ukraine demonstrates to the world the need to diversify energy supplies, British Prime Minister Gordon Brown said Thursday.

Events of recent weeks showed how a commercial dispute could impact across Europe, Brown told a news conference after talks with German Chancellor Angela Merkel in Berlin.

Merkel urged Russia and Ukraine to return to the negotiating table and resolve their differences so that gas supplies could be resumed as quickly as possible.

Calling the gas conflict a "serious development," Merkel said Russia risked losing some of its credibility in Europe if supplies continued to dry up.

The chancellor also stressed the need for the European Union to diversify its energy supplies, saying that more emphasis should be placed on renewable energy.

She said she would discuss the gas issue with Russian Prime Minister Vladimir Putin when he visits Germany on Friday.

Russia and Ukraine have been in a stand-off since January 1 over natural gas delivery terms. An effective Kremlin embargo on gas shipments to Ukraine has been in effect for three weeks and on transit shipments to Europe for eight days.

The lack of a contract between Russia and Ukraine regulating natural gas shipments into Ukraine is at the root of the crisis, with both Kiev and the Kremlin manipulating energy deliveries to Europe in an attempt to wring better contract terms out of their opponent.

Putin is due to meet Ukrainian Prime Minister Yulia Tymoshenko for talks on energy in Moscow on Saturday. (dpa)