Photo taken on March 27, 2021 shows the stuck container ship Ever Given on the Suez Canal, Egypt. At least 321 vessels are currently jammed around the Suez Canal awaiting salvage of the giant container ship Ever Given that has been stuck and blocking the vital waterway since Tuesday, Osama Rabie, chairman of the Suez Canal Authority (SCA), said Saturday. [Photo/Xinhua] SUEZ, Egypt - Efforts to dislodge a giant container ship blocking the Suez Canal have allowed its stern and rudder to move, but it remains unclear when the vessel will be refloated, the head of the canal authority said on Saturday. The 400 metre (430 yard) long Ever Given became wedged diagonally across a southern section of the canal amid high winds early on Tuesday, blocking one of the world's busiest waterways. A combination of dredging material from around the ship and pulling and pushing the vessel with tugboats made minor progress in dislodging the ship on Saturday, two SCA sources said. One source said there had been some movement at the bow of the ship. Suez Canal Authority (SCA) Chairman Osama Rabie told local TV that water had started running underneath the ship. "We expect that at any time the ship could slide and move from the spot it is in," he told a press conference earlier. About 15% of world shipping traffic transits the canal and hundreds of vessels are waiting to pass once the blockage has been cleared. Rabie said he hoped it would not be necessary to remove some of the 18,300 containers on board to lighten the ship's load, but strong tides and winds were complicating efforts to free it. "The ship's stern began (on Friday) to move towards Suez, and that was a positive sign until 11 p.m. (2100 GMT) at night, but the tide fell significantly and we stopped," Rabie told journalists in Suez. Dredgers removed some 20,000 tonnes of sand from around its bow by Friday. A Dutch firm working to free the vessel said it could be freed by the start of next week if heavier tugboats, dredging and a high tide succeed in dislodging it. Tugging attempts restarted on Saturday afternoon and further efforts were planned for Sunday, SCA sources said, though they added more sand may need to be removed from around the ship to free it. A shipping agent in Port Said said the SCA had notified agencies to prepare for the possible entry of new ships into the canal, while a shipping source said the SCA had outlined a plan for the rapid transit of 133 vessels once the Ever Given was freed.