Supporters of Turkish opposition celebrate in the streets after election victories

Recep Tayyip Erdogan and his party suffered their biggest upset in more than two decades on Sunday as the opposition swept municipal elections in Istanbul and other major cities. The Republican People’s Party (CHP) retained mayoral seats in two key cities – Istanbul and the capital, Ankara. The CHP also gained 15 new mayoral seats in cities across the country, advancing in locales that were previously strongholds of the Turkish president and his AK Party (AKP), marking the worst defeat since the latter came to power 21 years ago. Read the full story here: Subscribe to The Telegraph with our special offer: just £1 for 3 months. Start your free trial now: Get the latest headlines: Telegrap