The Ever Given, owned by Japanese firm Shoei Kisen KK, got wedged Tuesday in a single-lane stretch of the canal, about six kilometres north of the southern entrance, near the city of Suez.

At a news conference on Friday night at company headquarters in Imabari, western Japan, Shoei Kisen President Yukito Higaki said 10 tugboats were deployed and workers were dredging the banks and sea floor near the vessel's bow to try to get it afloat again as the high tide started to go out.

"We apologise for blocking the traffic and causing the tremendous trouble and worry to many people, including the involved parties," he said.

Shoei Kisen said in a statement on Saturday the company had considered removing its containers to get the weight off the vessel but it was a very difficult operation, physically speaking. The company said it may still consider that option if the ongoing refloating efforts failed.

A team from Boskalis, a Dutch firm specialising in salvaging, was working with the canal authority using tugboats and a specialised suction dredger at the port side of the cargo ship's bow. Egyptian authorities have prohibited media access to the site.

"It's a complex technical operation" that would require several attempts to free the vessel, Lieutenant General Osama Rabei, head of the Suez Canal Authority, said in a statement.

Attempts earlier on Friday to free it failed, said Bernhard Schulte Shipmanagement, the technical manager of the Ever Given.

The Suez Canal Authority has said it welcomed international assistance. The White House said it has offered to help Egypt reopen the canal.

An initial investigation showed the vessel ran aground due to strong winds and ruled out mechanical or engine failure, the company said. GAC, a global shipping and logistics company, had previously said the ship had experienced a power blackout, but it did not elaborate.

Bernhard Schulte said two canal pilots had been aboard when the ship got stuck. Such an arrangement is customary, but the ship's captain retains ultimate authority over the vessel, according to experts.

A maritime traffic jam grew to more than 200 vessels on Friday outside the Suez Canal and some vessels began changing course. More than 100 ships were still en route to the waterway, according to the data firm Refinitiv.

Apparently anticipating long delays, the owners of the stuck vessel diverted a sister ship, the Ever Greet, to head around Africa instead, according to satellite data.

Others also are being diverted. The liquid natural gas carrier Pan Americas changed course in the mid-Atlantic, now aiming south to go around the southern tip of Africa, according to satellite data from MarineTraffic.com.

About 10 per cent of world trade flows through the canal, which is particularly crucial for transporting oil. The closure also could affect oil and gas shipments to Europe from the Middle East.

Oil markets were absorbing the disruption for now, analyst Toril Bosoni said.

International companies are preparing for the effect that the canal's blockage will have on supply chains that rely on precise deliveries of goods.

Australian Associated Press