An Italian supply ship and its 11-member crew, seized in Libya last month, have been released unharmed, the vessel's operator and the Italian foreign ministry said on Saturday.

The ship was released by authorities in Tripoli late on Friday and made contact with an Italian naval vessel taking part in the Nato-led blockade of Libyan waters, Mario Mattioli, chairman of the operator Augusta Offshore said.

"We are very happy that the crew has been released. The last month has been a very uncertain time for us and even more for the crew and their families," he said in a statement.

The Asso 22, a supply vessel which had been working for a client of Italian oil group Eni, is crewed by eight Italians, two Indians and a Ukrainian.

It was detained on March 19, shortly before western aircraft began imposing a no-fly zone on Libya to prevent forces loyal to Muammar Gaddafi from harming civilians. – Reuters