Germany on Wednesday agreed to give coal and oil cargo precedence over passenger travel on railways in case of an energy crunch this winter due to a Russian gas squeeze.

Ministers from the centre-left-led coalition government said the shift in priorities was essential to ensure Europe's top economy can meet its energy needs.

"We have a shortage situation on the rails -- there's a real run on the rails right now, the rails are at full capacity," Transport Minister Volker Wissing told reporters.

"That means that if additional fuel transports are temporarily necessary we would have to prioritise them, which could mean that passenger trains would have to wait. That won't be an easy decision." 

Economy Minister Robert Habeck noted that part of the problem is that low water levels on major rivers like the Rhine have forced some cargo including coal and oil to be shifted off ships.

The prioritisation option, set for six months, would get fuel to power stations faster, he said.

Berlin and its EU partners have accused Moscow of "weaponising" energy supplies in response to Western sanctions over the Kremlin's war in Ukraine.

Germany, which is heavily dependent on Russian gas, has seen supplies slashed by 80 percent in recent months, triggering deep uncertainty about how it will keep the heat on and industry humming this winter.

Berlin has been scrambling to diversify supplies and has been forced to temporarily increase its reliance on other climate-warming fossil fuels as a stopgap measure.

"We want to free ourselves as quickly as possible from the grip of Russian energy imports," Habeck said.

The government is also imposing energy-saving measures throughout the country, including an upper limit agreed on Wednesday on the temperature of public administrative offices this winter of 19 degrees Celsius.