David Cameron 'seriously concerned' by Gibraltar events

Pedestrians and drivers cross the tarmac of the Gibraltar International airport in front of the Rock of the British Colony of Gibraltar on 4 August

Spain says a charge to enter and exit Gibraltar could be introduced

Prime Minister David Cameron is "seriously concerned" about the escalation of tensions at the Spain-Gibraltar border.

Spain has said it is considering a range of proposals including a new 50 euro (£43) fee to cross the border into the British territory.
Mr Cameron said none of the measures had been raised with the UK government.
Spain's latest move follows increased vehicle searches at the border last weekend, causing major delays.
In an interview with Spain's ABC newspaper, published on Sunday, Foreign Minister Jose Manuel Garcia-Margallo said Spain was considering charging people to enter and exit Gibraltar through its border post.

Mr Garcia-Margallo also hinted at the introduction of other measures, including tax investigations into property owned by Gibraltarians in neighbouring parts of Spain, and the closing of Spanish airspace to flights heading to Gibraltar.
Gibraltar's Chief Minister Fabian Picardo has accused Spain of "sabre-rattling".
He told BBC Radio 4's Today programme: "The things that Mr Garcia-Margallo has said are more reminiscent of the type of statement you'd hear from North Korea than from an EU partner.
"We've seen it before during Franco's time during the 1960s, but I think all of us hoped that those politics were never going to come back."
Gibraltar has linked Spain's hard-line stance to the creation of an artificial reef in waters off Gibraltar.
Mr Garcia-Margallo told the newspaper the proceeds from the border fee could be used to "help fishermen affected by the destruction of fishing grounds".
At the end of July, residents and tourists had to endure three days of delays at the border as a result of increased vehicle searches by the Spanish authorities. The government said it had a duty to prevent smuggling.
Spain disputes UK sovereignty over Gibraltar, a limestone outcrop on the southern tip of the Iberian peninsula, which has been ruled by Britain since 1713.