Foreign Secretary William Hague said the death of Mokhtar Belmokhtar would be a “blow to terrorism” but was unable to confirm reports that the al Qaeda commander had been killed in the north of Mali.
He told BBC's Andrew Marr: "It doesn't mean the problems of Mali would be at an end, there's a lot to do to promote a political process in Mali, elections, legitimate government and so on."
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The Prime Minister has praised the former soldier's "huge professionalism" in trying to save the life of Pc Keith Palmer.
The man who carried out the Westminster attack is thought to be British born and was once investigated by MI5, the Prime Minister has said.
Jason Day, who lost his father to stomach cancer at the age of 12, broke down in tears as he explained his shock exit during the WGC event.