BEIJING - Attacks by pirates and the number of ship seizures have been on the rise since March, a senior Chinese naval commander has said.

In March alone, 20 ships were hijacked in as many as 51 pirate attacks in the Gulf of Aden and waters off Somalia, Zhang Wendan, senior colonel and deputy chief of staff of the South Sea Fleet, said.

Zhang, who is also the commander of China's fifth escort flotilla sent to the Gulf of Aden, said pirates are using new tactics, as international organizations are making more efforts to ward off the threat from piracy, and commercial shippers have strengthened defenses.