Around 250 containers were flung over board from one of the vessels while the other caused an oil slick which spread more than 2 nautical miles from the ship.
The incident blocked the port, stranding incoming tankers due to the shut down.
The authorities have worked round the clock to clear the harbour of the submerged cargo while teams are still trying to contain the oil spill which is spreading due to windy conditions.
The crews from both ships were taken off to safety and an inquiry launched into the cause of the accident.