Low water has hampered shipping on most of the river south of Duisburg and Cologne, including the chokepoint of Kaub, traders said.

The Rhine is an important shipping route for commodities such as grains, minerals, coal and oil products, including heating oil. German companies faced supply bottlenecks and production problems in summer 2022 after a drought and heat-wave led to unusually low water levels on the Rhine.

Shallow water means vessel operators impose surcharges on freight rates to compensate for vessels not sailing fully loaded, increasing costs for cargo owners.

Water levels at Kaub are around 135 cm, down from around 350 cm in May. Last June, water levels fell below 120 cm and depleted to a critically low 32 cm in August 2022.

Deutsche Bank said in a note water levels below 135 cm mean a large container ship might have to reduce its load to around 50%.

In the years 2018-2020, water levels in mid-June were around 220-320 cm, Refinitiv Eikon data showed.

"A look at the current development of the Rhine's water levels brings back memories of the previous year, when there were massive problems for Rhine navigation during summer," Deutsche Bank economist Marc Schattenberg said in a note.

Rain forecast in river catchment areas in Germany this week could raise water levels, traders said, although shipping data provider Riverlake said the rain might not be enough to restore water levels to average depths.

(Reporting by Michael Hogan and Shadia Nasralla, editing by Barbara Lewis)