It has been dubbed a ‘‘crazy project’‘, but Turkish Prime Minister Tayyip Erdogan on Wednesday unveiled a mega canal scheme that aims to redraw the map of Istanbul.

Set to be completed by 2023, the vast waterway will stretch 50 kilometres and link the Black and Marmara Seas. Dwarfing both the Suez and Panama canal projects, the channel will be big enough for supertankers.

Speaking at a glitzy ceremony in the Turkish city just over a month before parliamentary elections, Prime Minister Tayyip Erdogan said: “Istanbul, from now on, will be a city which has two seas. With this project, there will be two peninsulas and one island in Istanbul.”

The canal is intended to cut heavy shipping congestion in the Bosphorus. Plans also include the building of a third airport in Istanbul. Turkey’s opposition, however, claims the schemes are aimed at enriching cronies in the ruling AK party.