March 5 (Reuters) - Negotiators from more than 100 countries completed a U.N. treaty to protect the high seas on Saturday, a long-awaited step that environmental groups say will help reverse marine biodiversity losses and ensure sustainable development.

The legally binding agreement to conserve and ensure the sustainable use of ocean biodiversity was agreed after five rounds of protracted United Nations-led negotiations that ended in New York on Saturday, a day after the original deadline.

"The ship has reached the shore," the U.N. conference president, Rena Lee, said after a marathon final day of talks. (Reporting by David Stanway in Singapore; Editing by William Mallard)