Turkish authorities closed the Bosphorus shipping channel yesterday to all traffic after a roll-on roll-off ship carrying liquefied petroleum gas sank due to bad weather, a shipping official said. Seven LPG tanks floated to the surface after the ship sank, two of them still posing a risk.

?Two tanks on the rocks ... still pose a danger?, Transport Ministry deputy undersecretary Baris Tozar told Reuters, saying a disaster had been prevented by precautions ? but also by luck. Ninety ships were waiting to enter the Bosphorus channel, including five vessels longer than 200m. Tozar said that the channel would be opened to traffic gradually.

The Bosphorus strait in northwestern Turkey passes Istanbul and is the only link for tankers carrying oil, grains and other commodities between the oceans and the Black and Marmara seas. Two years ago Turkey introduced regulations that vessels longer than 200 metres or carrying dangerous cargo could only pass during daylight hours.

The rules are mainly designed to protect the environment along the Bosphorus, which passes through densely populated Istanbul and is dotted with historic sites. Shippers and oil exporters have complained that delays due to the restrictions have driven up transit costs.