ANKARA, May 7 (Reuters) – Turkey’s President Tayyip Erdogan accused the opposition of being “pro-LGBT” at a rally in Istanbul on Sunday, as he stepped up his rhetoric against his opponents a week before what is expected to be a tight election. Elsewhere, protesters threw stones at Istanbul Mayor Ekrem Imamoglu, a member of the main opposition Republican People’s Party (CHP), during an election rally in the eastern city of Erzurum, a stronghold of Erdogan’s AK Party (AKP). Imamoglu later claimed nine people had been injured at the event. Turkey is due to hold presidential and parliamentary elections on May 14 and opinion polls show that Erdogan faces his biggest electoral challenge in his two decades in power. At his rally in Istanbul, the president was appealing to his conservative Muslim voter base.