DUBAI (Reuters) -Iran’s Revolutionary Guards have detained several foreigners, including Britain’s second most senior envoy in Tehran, for alleged acts of spying such as taking soil samples in restricted areas, state television reported on Wednesday. It did not say whether those detained were still under arrest. Britain said the reports were “completely false”. “These spies were taking earth samples in Iran’s central desert where the Revolutionary Guards’ aerospace missile exercises were conducted,” state TV said. The TV showed footage of Giles Whitaker and his family in central Iran where the…