The Sierra Leone-flagged ship, Kayan-I, is listing heavily to one side in the Bosphorus Strait after the collision

Two cargo ships have collided in Istanbul's Bosphorus strait, but the busy waterway remains open to traffic, GAC shipping agency says.

The M/V Kayan-I, a 5,644 tonne Sierra Leone-flagged general-cargo vessel, was taking on water in its stern and had
been towed to a secure position, after colliding with the M/V Adriablue in the southern part of the Bosphorus.

"Due to strong south wind M/V Kayan-I collided with M/V Adriablue while she was trying to anchor at Southern Bosphorus anchorage area," the shipping agency said in an email on Friday.

The M/V Adriablue sustained damage to its accommodation section.

Both the Bosphorus and Dardanelles straits were currently open to shipping traffic, the agency said.

The Bosphorus - the world's narrowest strait used for international navigation - divides Europe from Asia.

Its shores are heavily populated as Istanbul - Turkey's largest city - straddles it.