Emma Jones: "The govenment may find themselves under increasing pressure to make a formal protest"

It follows a protest by London after Spain refused to recognise Gibraltar driving licences and threatened to ban Gibraltar aircraft from using its airspace.

The move is a sharp escalation in a row over fishing rights around the Rock - a British dependent territory.

The BBC's Jon Devitt: There have been six-hour delays at the border

UK Foreign Office Minister Joyce Quin confirmed Foreign Secretary Robin Cook had spoken to Gibraltar's chief minister to offer him full support.

She said the UK "will continue to defend with determination Gibraltar's legitimate rights" in the face of Spanish restrictions on border movements prompted by the fishing dispute.

Spanish border guards have refused entry to at least two Gibraltar drivers saying they do not hold licences valid in Spain.

Ms Quin stressed the UK's good relationship with Spain, although she said Spanish authorities had to respect the people of Gibraltar.

She said: "We believe that it is everyone's interests that relations between Spain, Britain and Gibraltar improve and harassment is counterproductive."

The government would be raising the dispute through diplomatic channels with the government in Madrid and would also pursue the issue through the European Union, Ms Quin said.

Shadow Foreign Secretary Michael Howard, who called for the statement, said the whole pattern of the government's dealings with Spain was "one of equivocation, retreat and surrender".

Foreign Office Minister Joyce Quin MP: "This agreement builds on an earlier understanding by the two governments"

Mr Howard called for the government to show "the resolve and the determination that are overdue".

He claimed Ms Quin had "conspicuously failed" to condemn Spain's behaviour.

He asked: "Can you confirm reports in this morning's newspaper that Spanish proposals for joint sovereignty with Gibraltar have been languishing in the foreign secretary's in-tray for more than a year?"

MPs also heard how one man had been denied permission to cross the border as his wife was about to give birth.

Lindsay Hoyle, Labour MP for Chorley, described how three of his constituents not being allowed to enter Spain or return to Gibraltar for 13 hours.

Ms Quin said: "There have been some human tragedies and human difficulties associated with the delays which have been imposed at the border."

The British Foreign Office says it is complaining to Madrid as Gibraltar licences are valid within the European Union and must be recognised by EU member states.

A Foreign Office spokeswoman said the British Ambassador in Madrid, Peter Torry, has registered a formal protest with the Spanish Government over the driving licence issue.

She said: "We want to see this issue resolved peacefully and without confrontation, but not at the expense of the rights of the people of Gibraltar."

She added that the threat by Spanish Foreign Minister Abel Matutes to ban Gibraltar aircraft from flying over Spain was "extraordinary and unprecedented".

BBC Political Correspondent Nick Jones: "This deal has upset the fishermen"

The Spanish measures represent the deepening of a crisis triggered by a dispute between Spanish fishermen and the Gibraltar authorities over fishing rights.

Spanish fishermen blocked the Gibraltar border for 16 hours when one of their boats was seized for illegal fishing.

The dispute was defused with an agreement between the Gibraltar authorities and the local fishermen.