The Spanish Ambassador in London, Federico Trillo, in a secret meeting, has given a guarantee that no Spanish ship would enter Gibraltar territorial waters.
It follows a bilateral incident provoked by the Spanish Oceanographic Boat, Ramon Margalef, in waters claimed by Gibraltar.
The news of the secret meeting was broken in the House of Lords by the British Secretary of State for Foreign Affairs, Seyeeda Warsi.
She said Trillo was called to explain when they saw the scientific boat at 250m from the rock.
The promise was made in a meeting, unknown before now which took place last November and where Trillo was called to transmit to his government the British feeling of disloyalty, and that was when Trillo said it would not happen again.
Since then there has been no confrontation and no Spanish vessel has entered the 3 nautical mile limit around the isthmus claimed by Gibraltar.
Spain’s claim only recognises their authority over the inland waters of the old port, as stipulated in the Treaty of Utrecht in 1713.