Egypt's Suez Canal Authority on Saturday evening said that 321 ships are now waiting to pass through the vital trade route, which was blocked on Tuesday by a massive container ship wedged diagonally across the waterway. The blockage has halted upward of $400m of trade an hour as international salvage crews and US military experts join the effort to refloat the<em> Ever Given</em>, a 400-metre long, 200,000-tonne vessel that became stuck shortly after entering the canal. New video shot by a satellite shows tugboats trying to free the giant cargo ship. "The Suez canal traffic jam is visible from space," Airbus Space, a space technology company, said on Twitter, after posting satellite imagery. Tugs managed to shift the stricken vessel 29 meters on Saturday and dredgers succeeded earlier in freeing the propellers from the sediment that has glued the vessel to the canal's banks. The video, shot by Planet Labs Inc, captured the work around the <em>Ever Given,</em> including dredgers, tugboats and digging efforts alongside the canal. The European Space Agency on Friday also released space images of the traffic jam of ships waiting to pass through the Suez. Two Suez pilots were on the ship at the time it ran aground and officials have blamed strong winds and a sandstorm. However, Admiral Oussama Rabieh, Chairman of the Suez Canal Authority, said that technical or human error could have contributed. “When it comes to big accidents like this one, there is always more than one cause. The investigation could reveal a human error or a technical fault,” he said on Saturday. No formal investigation into how the accident occurred will begin before the ship is refloated and traffic returns to normal, he said. At a press conference in Japan on Friday, Yukito Higaki, president of Shoei Kisen, which owns the <em>Ever Given</em>, said there were no signs of damage to its engines and instruments. <em> </em> <em>Additional reporting by Sarwat Nasir</em>