Turkey's Bosphorus strait, one of the world's busiest shipping lanes, will be closed during the June 28-29 Nato summit in Istanbul for security reasons, a Turkish political source said on Thursday.
US President George W. Bush, British Prime Minister Tony Blair and nearly 40 other leaders are due to attend the summit in the city of 10 million, which suffered four devastating al Qaeda-linked bombings last November.
The Bosphorus is the only sea exit for some 2.5 million barrels of Russian crude oil each day, as well as other commodities such as grain from Black Sea states.
Repeated closures in the Bosphorus and the Dardanelles straits at the southern end of the Sea of Marmara caused massive congestion during the winter months, forcing companies to pay demurrage costs of up to $60,000 a day.