By Leo Sands
BBC News

A rollercoaster crash at Legoland's theme park in Germany has hurt more than 30 people, at least one of whom has severe injuries.
According to the park, the accident happened after two rollercoaster trains collided with each other.
The incident took place on the Fire Dragon ride at the leisure resort, which is near Gunzburg in Bavaria.
Legoland said it had immediately started a full investigation and the ride will be closed for the time being.
The company said the accident happened after one rollercoaster train stopped and another train "did not stop completely for until now unknown reasons and made impact".
A total of 38 people were in both trains, the park said – with 31 of them suffering minor injuries. Of those, 14 went to hospital for further observation and one person needed further treatment.
Three helicopters were deployed to the scene, German media reports.
Riders still trapped on the rollercoaster had to be evacuated after the incident with the help of two fire engines.
"All told, the accident was quite mild," said the Bavarian Red Cross, which was involved in the emergency response.
According to Legoland's website, the Fire Dragon ride is suitable for children aged six and older who are accompanied by adults, and eight years and older when unaccompanied.
The rollercoaster train, which is designed to look like a fire-breathing dragon, passes through a dark indoor area before emerging outside to a large, twisting track at speeds of up to 29km/h (18mph).
In a statement, Legoland Germany – which will open again on Friday – said: "The staff immediately followed well-rehearsed safety procedures and guests were immediately evacuated from the trains and attended by trained resort staff.
"Legoland emergency personnel as well as paramedics, doctors, the police and the fire fighters were at site within few minutes. The park area was evacuated."
"We want to thank all emergency personnel showing great commitment at site today and we want to wish a quick recovery to everyone involved," added the park's divisional director Manuela Stone.
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