A joint naval operation to sweep for mines off Estonia has turned up 64 of the weapons since it was launched on August 31, officials said. Dating mainly from the two world wars, the mines were discovered in Tallinn Bay and around Hiiumaa island in the latest of the annual Nato exercises in the Baltic dubbed Open Spirit.

On Wednesday, crowds flocked to the shores of Tallinn Bay near the Estonian capital to watch some of the devices being detonated two kilometres off the coast.

The current exercises which ends today involved 16 warships from Denmark, France, Germany, Lithuania, Poland and Sweden as well as hosts Estonia, backed by divers from Estonia, Germany and the United States. Minesweeping exercises in the Baltic with the region's Nato members playing host in rotation have been organised since 1994, with nearly 600 mines being found in total.

However, an estimated 80,000 mines are still lying at the bottom of the sea, most of them laid in World War II, as a potential threat to passing vessels.