Syria has asked the United Nations to "prevent any aggression" against it. The request was in a letter from the UN ambassador Bashar Ja'afari, the state news agency SANA reported.
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The royal couple have been in the US to mark the 300th anniversary of the foundings of New Orleans and San Antonio.
A small number of people were treated at Southgate Tube station, British Transport Police said.
Police and coastguard discovered the bodies of 42-year-old Cheryl Tompsett and her five-year-old son Leo Tompsett on Monday.