Spanish and Moroccan coastguards rescued Tuesday 54 illegal migrants who were trying to reach the southern coast of Spain on inflatable boats, Spain's maritime rescue service said.

That brings to nearly 300 the number of migrants who have been plucked from inflatable boats since Friday as they tried to cross the Strait of Gibraltar separating Spain from Morocco.

Drivers fumed in hours-long queues Tuesday to cross into the tiny British outpost of Gibraltar from Spain as tensions mounted between Madrid and London over the disputed territory.

"At present the incoming queuing time is over three hours. All documents being checked," the Royal Gibraltar Police said in a Twitter message.

The British government is considering taking legal action against Spain over stringent border checks imposed at the border with Gibraltar, a spokesman for Prime Minister David Cameron said Monday.

The spokesman said the checks by Spanish guards, which have caused tailbacks of several hours at the border of the British-held territory, were "politically motivated and totally disproportionate".

Spanish and French police said Saturday they have dismantled a human trafficking ring that smuggled Chinese migrants into Europe and the United States, arresting 75 suspects including "main operatives" based in Barcelona.

Fifty-one suspects were arrested in Spain and 24 in France after a two-year joint investigation, a police statement said.

Spain said Friday it is reviewing its railway network to boost safety after a train derailed last month killing 79 people, the country's deadliest train disaster in decades.

"Everything is under review and subject to proposals for improvement," Public Works Minister Ana Pastor told a parliamentary panel about the July 24 crash.

Spain will take "all necessary measures" to defend its interests in Gibraltar, Prime Minister Mariano Rajoy said on Friday amid a row with London over the British outpost on Spain's southern tip.

"We will take legal measures which are proportionate to defend the interests of Spaniards," he said after a meeting with Spain's King Juan Carlos on the Mediterranean island of Majorca.

British Prime Minister David Cameron on Wednesday warned his Spanish counterpart that the escalating tit-for-tat over border tensions in Gibraltar risked damaging relations between their countries.

Cameron and Mariano Rajoy discussed ways to calm the situation in a call Britain described as "constructive" after tensions rose at the weekend when Spanish Foreign Minister Jose Manuel Garcia-Margallo threatened to impose steep tolls to cross the border.

The European Commission said Tuesday it would send a team of monitors to the Spain-Gibraltar border as perennial frontier spats resurfaced.

Commission spokesman Frederic Vincent said the EU "has informed the Spanish authorities of our intention to send Commission experts to the border."

A judge remanded in custody Tuesday a convicted child rapist who was arrested in Spain after a controversial pardon by Morocco's king was revoked in the face of angry protests.

The judge ruled that Daniel Galvan Vina, a Spanish national found guilty of raping 11 children aged between four and 15 in Morocco and sentenced to 30 years in prison there, was a flight risk and would remain in custody while his extradition was being considered, the court said.

The royal pardon may have been revoked but residents of the Moroccan city of Kenitra still want to know why a man convicted of raping their children was ever released.

Spanish pedophile Daniel Galvan Vina, who lived in their midst for years, was found guilty of raping 11 children aged between four and 15, and jailed for 30 years in September 2011.