Earlier this week, the Iranian oil tanker Grace 1 was given permission to leave Gibraltar after spending a month in detention after it was seized by UK marines.
Watch Iranian oil tanker Grace 1 leaving Gibraltar, a month after it was formally detained on suspicion of breaching EU sanctions against Syria.
Commenting on the issue, acting Spanish Foreign Minister Josep Borrell claimed that the vessel was detained at the request of the United States, which has long been seeking to curtail Iranian oil exports.
The Gibraltar government later confirmed that Washington had made a last-minute request to halt the release of the seized Iranian vessel on a number of allegations.