An attempt to rescue Ever Given has caused the stern and its rudder to move, but it is not clear when the ship stops being trapped.

Two sources from the Suez Canal Authority (SCA) said they were dredging around the ship and towing Ever Given with a tugboat.

A tugboat participated in an effort to rescue the ship Ever Given on March 27.

SCA President Osama Rabie said water had begun to flow underneath the ship.

About 15% of world ocean traffic goes through the canal and hundreds of boats are waiting to pass when the congestion is cleared.

"The stern on March 26 started moving towards Suez, which was a positive sign until 23:00, but the tide retreated significantly and we had to stop," Rabie said.

The large container ship Ever Given, a total tonnage of more than 200,000 tons, crashed across the banks of the Suez Canal and ran aground on the morning of March 24 when moving from the Red Sea to the Mediterranean.

The dredgers removed about 20,000 tons of sand from around the bow on March 26.

Rabie said the 321 ships are waiting to go through the Suez Canal, including dozens of container ships, cargo ships, liquefied natural gas carriers (LNG) or liquefied petroleum gas (LPG).

Fourteen tugboats joined the rescue effort, however Smit Salvage and its parent company Boskalis warned that using too much force to pull the ship could damage it.

Boskalis CEO Peter Berdowski said the crane could be used to reduce the load for Ever Given by unloading containers, although experts warning this process could be complicated and prolonged.

"If we do not succeed next week, we will have to remove about 600 containers from the bow to reduce the weight," he said.