Madrid - Spanish Prime Minister Pedro Sanchez has said he would vote against Britain's draft Brexit deal if no changes were made to reflect negotiations about a dispute over Gibraltar.

Sanchez has said if article 184 of the agreement had been not revised by the special EU summit on Brexit, he would vote "no" on endorsing the deal.

More "legal clarity" needed

Spanish Foreign Minister Jose Borrell has made similar comments, saying the draft deal needed more "legal clarity."

Gibraltar lies on Spain's southern coast and has been a British Overseas Territory since 1713. Spain has repeatedly laid claim to it.

"Gibraltar does not belong to the United Kingdom, it is represented by it, but it does not belong to it," Sanchez said.

Political declaration

The remaining 27 EU leaders are set to endorse the withdrawal deal reached by Brussels and London last week at a special summit on Sunday. A political declaration outlining the future relationship between Britain and the EU is also expected to result from the summit.

Spain says the current draft does not clarify that future negotiations on the relationship between Britain and the EU will be conducted separately from negotiations on the status of Gibraltar.

Madrid wants direct negotiations between Spain and Britain to be clearly enshrined in the deal.

European Commission spokesman Margaritis Schinas said Brussels was aware of Spain's concerns.

"The issues expressed by Spain are issues that are known to us," said Schinas, adding, "We are working on them."

The endorsement

Negotiations are ongoing to ensure that the withdrawal agreement, as well as an accompanying political declaration on future relations, can be finalized this week, he noted.

The next stage in the procedure is the planned endorsement of the withdrawal agreement at a special EU summit on Sunday, after member states had approved the text on Monday "with a number of concerns expressed," Schinas added.