"We must think about the consequences of shutting down nuclear power plants," Merkel said on Tuesday in an interview with Germany's public broadcaster ARD.
The gradual shutdown of all Germany's nuclear power plants was agreed upon in 2000 by the government of former Social Democratic Chancellor Gerhard Schröder and his coalition partners at the time, the Greens.
According to Merkel, however, the latest incident regarding the transit of Russian oil supplies through Belarus demonstrated "that we need a comprehensive, balanced energy mix in Germany."
Merkel did not directly criticize Moscow but said Berlin would engage in "intensive discussions" about the energy issue.
"I will travel to Moscow on Jan. 21 and will discuss this issue with the Russian president," Merkel added.
The German chancellor, who is presiding over Germany's six-month EU presidency, said Berlin would play a key role in EU talks with Moscow regarding a new Partnership and Co-operation Agreement with Russia.
A divided coalition
Merkel's Christian Democrats (CDU) and their coalition partners, the Social Democrats (SPD), have been divided over nuclear power. While conservatives near Merkel have repeatedly demanded that Germany slash a scheduled nuclear energy phase-out, the SPD remains in favor of the plan to close nuclear power plants.
"Those who use oil shortages in order to propagate nuclear energy are not capable of intellectually comprehending the topic of energy supplies," said Ulrich Kelber, deputy president of the SPD parliamentary bloc.
Members of the opposition Greens also protested the idea of making changes to the planned nuclear phase-out.
"With uranium, you can neither heat your homes nor fuel your cars," said Green politician Jürgen Trittin.
Belarus ready to negotiate
Meanwhile, a delegation headed by Belarus' deputy prime minister, Andrei Kobyakov, joined other officials, including Deputy Economic Development Minister Vladimir Naidunov, who arrived in Moscow late Monday, the Belarus embassy told the AFP news agency.
Belarus says it is ready to negotiate over a demand that Russia pay $45 dollars (35.50 euros) per ton transit fees on oil sent through its territory to EU countries. Moscow has refused to pay and on Monday supplies to Germany, Poland and Slovakia were interrupted.
Russian officials have not yet confirmed they are ready to negotiate and insist that the transit tax is illegal.
Belarus has long maintained close ties with its giant eastern neighbor Russia. The two countries have officially been building a "union state," and Moscow has seen Belarus as a buffer against the expansion of the NATO military alliance.
But recently relations have become strained, particularly since Moscow decided to double the price it charges Belarus for natural gas from the start of this year.
Russia also introduced a tariff on oil exports to Belarus, which refined the cheap oil and sold it to Western countries. In retaliation, Belarus imposed the oil transit tax.
The Russian newspaper Gazeta voiced sympathy for Belarusian President Alexander Lukashenko, saying that the introduction of the oil transit fee was a "symmetrical" step in response to "severe political pressure" from Moscow.
The paper noted however that Lukashenko lacked the Western backing given to another Russian neighbor, Ukraine, during an energy dispute last year, and said, "It would be better for everyone if the war finished" on Wednesday, when, Belarusian Prime Minister Sergei Sidorsky is due in Moscow.
Germany's reliance on Russian energy
The Druzhba pipeline supplies about 20 percent of Germany's annual oil imports, or 23.4 million tons in 2005, according to the German oil industry federation (MWV).
Russia has reduced the amount of oil it transits through western neighbors Belarus and the Baltic states, preferring to send oil via a new terminal near Saint Petersburg as well as around the coast of Norway -- in spite of less favorable climatic conditions.
Meanwhile on Monday the energy-rich state of Azerbaijan said it had stopped exporting oil to southern Russia due to a natural gas price dispute with the Russian gas giant Gazprom.
Mukhtar Babayev, an official with Azerbaijan's state oil firm SOCAR, said Azerbaijan was using oil previously exported to Russia -- about 4.2 million tons in 2006 -- to fuel power stations that could no longer run on Russian natural gas following a breakdown in the pricing talks.