Ukrainians are widely expected to give a resounding endorsement to the overthrow of their last elected leader by voting for presidential candidates promising close ties with the West, in defiance of Russia's Vladimir Putin.
But the absence of more than 15 percent of the electorate, in Russian-annexed Crimea and two eastern regions where fighting with pro-Moscow rebels continued on Saturday, may mar any result.
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A British family believed to have fled to Syria have joined Islamic State, according to a statement said to be released on their behalf.
After the heatwave come the storms, with lightning flashes illuminating the night sky across much of the country last night.
An Independence Day event at a UK base has been cancelled by the US Air Force over security fears.