President Obama has called for calm as protests over the death of a black teenager in America at the hands of police rage on.
In a speech at the White House today, he said he knew emotions were "raw" and said maintaining public safety, while allowing people the right to protest, was a priority.
The President also used the speech to condemn any "excessive force" used by officers when tackling peaceful protesters.
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It follows a similar move by ministers in Scotland.
A "small number of people" have been treated following a "reported minor explosion" at Southgate tube station in London, police said.
The EU and UK have released a joint statement on how negotiations are progressing.