PARIS, France (CNN) -- Pirates have released a French merchant ship and its nine crew members seized off the Nigerian coast over the weekend, the ship's owners said Wednesday.
China has reportedly been working to rapidly modernize its fleet.
The announcement came as two Chinese destroyers and a supply ship joined the growing international naval coalition patrolling the waters in the Gulf of Aden off Somalia.
The crew members of the Bourbon Leda are all in good health, Paris-based Bourbon said in a news release. They will be "rapidly reunited" with their family and friends, the company said.
Pirates captured the Bourbon Leda, a supply vessel, on Sunday. A Bourbon spokesman refused to comment when asked by CNN whether the company had paid a ransom for the ship's release.
Pirates in neighboring Cameroon seized another Bourbon ship, the Bourbon Sagitta, and 10 of its crew members in October. They released the vessel and its crew 11 days later.
Bourbon specializes in offshore oil and gas shipping and dry bulk transport.
Meanwhile, the Chinese convoy -- which left some two weeks ago on a mission to protect Chinese merchant ships from an increasing number of pirate attacks occurring in the gulf -- has received requests for help from at least 15 vessels, according to news reports.
It marks the first time Chinese naval vessels have left Chinese waters in centuries. They will will join a multinational naval force already patrolling the area, including vessels from the United States, NATO member states, Russia and India.
Rear-Admiral Du Jingchen, the fleet's commander, told Xinhua news agency the escort mission has started.
The fleet began escorting four ships -- one from Hong Kong and three from mainland China -- through the gulf on Tuesday afternoon, the China Shipowners' Association told the South China Morning Post.
Fifteen ships have applied for protection including some from Hong Kong, said a director of the Ministry of Transport, He Jianzhong, according to the Hong Kong-based newspaper.
Figures from the International Maritime Bureau for the year-to-date show pirates have attacked almost 100 vessels and hijacked nearly 40 off the coast of Somalia.
The all-important Gulf of Aden links the Indian Ocean and the Red Sea. Around 20,000 oil tankers, freighters and merchant vessels pass along the crucial shipping route each year.
China's navy is considered a "brown-water fleet" -- designed to operate almost exclusively along its coast. But the country has reportedly been working to rapidly modernize its navy for the past several years.
Chinese officials have said their mission would last as long as is necessary and in accordance with U.N. Security Council regulations.
The U.N. Security Council passed a resolution in December aimed at combating piracy along the Horn of Africa by allowing military forces to chase pirates onto land in cases of "hot pursuit."
Among the victims of pirate attacks have been cargo ships, oil tankers and luxury yachts.
At least one major company pulled its ships from the Gulf of Aden region this year, meaning cargo bound for Europe had to round the African continent rather than use the Suez Canal.