Turkish President Recep Tayyip Erdogan on Friday opened the world's longest suspension bridge over the Dardanelles strait in northwestern Turkey -- which cuts travel time between Asia and Europe to six minutes. 

The 2.5-billion-euro ($2.8-billion) "1915 Canakkale Bridge" built by a consortium of Turkish and South Korean companies has a main span of 2.023 kilometres (1.257 miles) between its towers painted in the red and white colours of the Turkish flag, making it longer than the previous recordholder, the Akashi Kaikyo Bridge in Japan.

Erdogan has often boasted of mega infrastructure projects, including a third bridge over the Bosphorus, throughout his two-decade rule first as prime minister and then president. 

The Turkish leader uses them as a means to drive economic growth as he eyes a re-win in presidential elections in 2023. 

The inauguration coincides with the 107th anniversary of Ottoman forces' naval victory against British and French troops in the Gallipoli campaign during World War I.  

In his speech, Erdogan said the bridge would "keep alive the memory of Dardanelle martyrs."

Erdogan is also planning to build a canal in Istanbul -- an alternative to the Bosphorus. 

Opponents accuse him of pursuing a vanity project that will open up Istanbul to unbridled construction and put the government into deep and largely unnecessary debt.