An aerial view shows coal at a dry bulk terminal of German Rheinberg-Orsoy harbor along Europe’s most important shipping way Rhine in Rheinberg near Duisburg, Germany, April 6, 2022. Picture taken with a drone. REUTERS/Stephane Nitschke/File Photo

Germany plans to give the transportation of materials and equipment essential for energy production priority on the country's rail networks should water levels on the Rhine fall further and hamper shipping by river, a draft decree shows.

DB Netz, the rail network arm of railway operator Deutsche Bahn, has already rejigged usage conditions to give preference to trains carrying mineral oil products and hard coal for power generators as Germany tackles an energy crisis.

"The aim is to ensure the ongoing operations of power stations, refineries, electricity grids and other system-relevant infrastructure," said the draft drawn up by the transport and economy ministries and seen by Reuters.

It also referred to gas and transformer equipment for power production and transmission to be given priority over passenger services and other industrial requirements.

Germany's government cabinet has to approve the provisional legislation that would be limited to six months, the draft said.

Water levels on the Rhine are low because of unusually hot and dry weather, making it impossible for many vessels to navigate the critical shipping route fully laden.

This has coincided with a shortage of gas for power stations, heating and industrial processes due to reduced Russian exports has led to temporary switches by operators back to more coal and oil usage.

"We need extraordinary measures to ensure supply security," economy minister Robert Habeck in a statement.

An important reference waterline level at the chokepoint of Kaub near Koblenz stood at 34 centimetres at midday (1000 GMT) on Sunday, 3 cm lower than the same time on Saturday.

Kaub hit 25 cm at one point in 2018.