The US State Department is in conversations with the Ukraine government to stipulate requirements for a humanitarian aid convoy from Russia to cross borders.
Deputy spokesperson Marie Harf said the International Red Cross would take control of the aid and distribute it once the convoy crossed the border into Ukraine.
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Temperatures will reach around 28 Celsius (82F) at their highest.
A minute's silence will be observed at 11am on Thursday in remembrance of those who lost their lives in the Manchester Arena attack.
New research has found those who consumed two cups had a 35% reduced risk, and for those who drank five cups, the risk halved.