Spanish Prime Minister Mariano Rajoy and British Prime Minister David Cameron agreed Wednesday to have their foreign ministers hold "immediate" talks to reduce tensions over Gibraltar.

Rajoy and Cameron spoke by telephone in the wake of recent bilateral problems over the British Crown Colony.

Gibraltarian tugboats dropped 70 huge concrete blocks into the sea near the Spanish town of La Linea de la Concepcion two weeks ago to create an artificial reef in Spanish waters near the Rock, prompting complaints from Spanish fishermen and leading to an investigation by Spain's special prosecutor for environmental crimes.

Spain tightened border controls last week, causing long delays for Gibraltarians and upsetting officials on the Rock and in London.

Spain's Foreign Ministry said Gibraltar was not part of the Schengen Area, or EU Customs Union, and therefore the border controls at the Rock "are unavoidable" for the Iberian nation.

Spain contends that the controls were necessary to avoid illicit traffic.

Rajoy and Cameron agreed that the dispute with Gibraltar, a British colony since the 18th century over which Spain claims sovereignty, should not affect bilateral relations.

Rajoy made a commitment to reduce the border controls and "the two leaders agreed that a solution should be found to the dispute over fishing," the British government said.

The Spanish prime minister reminded Cameron that the border controls complied with the Schengen Area rules and were non-discriminatory, the Spanish government said.

Gibraltar, a territory of 5.5 sq. kilometers (2.1 sq. miles) at the entrance to the Mediterranean Sea, has been held by Britain since 1704 and became a British Crown Colony in 1713 under the Treaty of Utrecht. EFE