++CLIENTS PLEASE NOTE: THIS VIDEO HAS BEEN LOOPED++ Nearly 100 firefighters and 15 fire engines are battling a huge fire at a five-star hotel in London.<br /><br />The footage, captured this afternoon, shows huge plumes of smoke coming from the Mandarin Oriental hotel in Knightsbridge.<br /><br />London Fire Brigade said the cause of the fire is not known at this stage.
