Britain will continue backing Gibraltar amid a border spat with Spain and cares "deeply" about the people of the British Overseas Territory, Prime Minister David Cameron said here Friday in talks with the top Gibraltarian elected official.

Cameron received Gibraltar Chief Minister Fabian Picardo at the British leader's official 10 Downing Street residence.

The European Commission plans an investigation in response to complaints about hours-long waits at the Spain-Gibraltar border since Madrid imposed new checks

A separate EC probe requested by Spain will look into the use of concrete blocks to create an artificial reef off the British Crown Colony sitting at the tip of the Iberian peninsula.

The dropping of 70 concrete blocks into the Mediterranean violates the European Union's environmental regulations and threatens the livelihoods of Spanish fishermen, Madrid says.

"Britain will always stand up for Gibraltar," Cameron told Picardo. "We will always stand up for the interests of the people who live in Gibraltar."

"It is something that matters to us very deeply," the British leader said.

"The people of Gibraltar know they have a friend in David Cameron and a friend in (British Foreign Secretary) William Hague," Picardo said.

Cameron and Picardo "discussed the unacceptable delays at the Spanish/Gibraltar border and agreed that these are damaging to the people and economies of Gibraltar and Spain," a No. 10 spokeswoman said after the meeting.

"They agreed that efforts should remain concentrated on finding a diplomatic solution, in line with the Foreign Secretary's proposals last year for ad hoc dialogue," she said.

Spain insists the new border checks are legal and necessary because neither Britain nor Gibraltar is part of the Schengen Area, which allows passport-free travel across borders, and because London chose to exclude the Rock from the European Customs Union.

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