A fresh effort is under way to refloat a giant container ship blocking Egypt's Suez Canal.

Canal authorities say 14 tugboats are trying to take advantage of Saturday's high tide and more will arrive on Sunday if today's attempt fails.

The Ever Given became wedged in the canal - one of the world's busiest waterways - on Tuesday.

More than 300 ships are stuck on either side of the blockage. Some ships have had to reroute around Africa.

By late Friday, dredgers had removed about 20,000 tonnes of sand from around the Ever Given's bow, which was stuck deep into the canal's bank.

The Suez Canal Authority (SCA) has brought in Netherlands-based Smit Salvage to help the effort.

Peter Berdowski, chief executive of Smit's parent company Boskalis, said the bow was "really stuck in the sandy clay, but the stern has not been pushed totally into the clay, which is positive".

"We can try to use that as leverage to pull it loose," he told Dutch TV programme Nieuwsuur on Friday.

"We hope that a combination of the tugboats, dredging of sand at the bow and a high tide will enable us to get the ship loose."