Specifically, three tonnes of fuel leaked overboard during bunkering operation in Sines, Portugal on April 5, when fuel was pumped from bunker tanker Bahia Tresto container ship MSC Sandra, at Terminal XXI.

When the incident occurred, the anti pollution operation was activated. Consequently, the oil spill was rapidly contained, preventing the possibility of its spreading.

For the time being, the factors that caused the accident remain unknown.

Nuno Mascarenhas, the Mayor of Sines, reported that the spill occurred 'during the transfer of fuel'.

Booms were deployed in order to contain the spilled fuel in order to minimise impact on port activity.

Authorities are currently carrying out clean-up activities and an investigation into the incident is underway.