Maersk can no longer transport goods in or out of Qatar after Arab countries imposed restrictions on trade with the tiny Gulf state and the company is looking at alternative shipping routes.
Shipping lines normally transship cargoes from the United Arab Emirates port of Jebel Ali to Qatar, which relies heavily on imports by sea and land.
A Maersk Line spokesman said on Tuesday: "We have confirmation that we will not be able to move Qatar cargo in and out of Jebel Ali."
"We expect disruptions to our Qatar services. The situation is very fluid," the spokesman said, adding that Maersk would notify customers about alternative options as soon as possible.
The spokesman said the company, which is the world's biggest container shipping line, was looking at other routes such as Oman.
Larger container ships are unable to dock at ports in Qatar due in part to shallow waters so shipping lines use feeder services, which transport container boxes from the larger port of Jebel Ali in the United Arab Emirates.
Saudi Arabia, Egypt, the UAE and Bahrain severed relations with Qatar and closed their airspace to commercial flights on Monday, in the worst split between powerful Arab states in decades.
Ports have also been directly affected, which has disrupted trade in commodities from crude oil to metals and food.
The ban has meant that any ship sailing to and from Qatar will be prevented from calling at major ports in the UAE and Saudi Arabia, which include Jebel Ali, as well as Bahrain.
Food imports have been affected as Saudi Arabia closed its land border with Qatar, stranding thousands of trucks carrying supplies.
Trade sources said the UAE and Saudi Arabia have already cut exports of white sugar to Qatar. Consumption is traditionally higher during the Muslim holy month of Ramadan, which is currently being observed.
(By Jonathan Saul; Editing by David Clarke and Jane Merriman)