The European Union has decided to block Icelandic fishing vessels carrying mackerel from landing at its ports in an escalation of a dispute over fishing quotas.

The European Commission, the executive of the 27-member EU, formally notified the European Economic Area of plans for the ban, the final step before enforcing it.

“We have informed the EEA joint committee that we will implement the landing bans without further delay,” commission spokesman Oliver Drewes told Reuters.