A freight terminal in Germany operated by Kuehne + Nagel International, the world’s second-largest freight forwarder by revenue.

Several of the world’s largest freight forwarders have suspended services to Russia, citing growing restrictions from shipping lines and air carriers that are cutting off the country’s access to global trade lanes over Moscow’s invasion of Ukraine.

Switzerland-based Kuehne + Nagel International AG and Germany’s DB Schenker both said in customer advisories they are halting deliveries to and from Russia by air, land and sea. Denmark-based DSV A/S and France’s Geodis said they were also suspending deliveries to Moscow ally Belarus.

“Knowing that today’s decision to suspend transport to and from Russia and Belarus will further add to the supply chain disruption and complexity for our customers, we want to underline that…we are doing our utmost to alleviate the negative supply chain effects from these measures,” DSV said in a notice on Thursday.

Digital cargo marketplace Freightos said the disruptions in services and in transportation connections to Russia, along with rising oil prices, threaten to further drive up shipping costs for companies world-wide.

Some airfreight carriers are already introducing war-risk surcharges to cover rising operating costs, Freightos said in a report Thursday. The diversion of ocean freight shipments to other ports “is already resulting in pileups at origin ports in Europe and elsewhere, possibly causing congestion and increasing rates on these lanes,” the company said.

DHL, a unit of Deutsche Post AG , had earlier halted handling of inbound shipments for Russia.

DHL, Kuehne + Nagel, DB Schenker and DSV are the world’s four largest freight forwarders by revenue, according to research group Armstrong & Associates, and Geodis is the No. 9 logistics provider.

Container shipping lines A.P. Moller-Maersk A/S, Mediterranean Shipping Co. and CMA CGM SA had earlier this week suspended their freight services to and from Russia, with exceptions for foodstuffs, medical shipments and humanitarian aid.

Many major freight operators have already frozen operations in Ukraine, closing offices and telling workers there to remain home.