Killings of environmental activists have risen by 20% in the last year, according to campaign group Global Witness.
Last year saw a spike in killings related to hydropower programs. Fourteen people died defending their land and rivers against dam projects.
The Philippine Senate is also investigating accusations that an American government contractor dumped about 50,000 gallons of untreated domestic waste from a Navy ship near Subic Bay after joint exercises in October. The contractor has denied the allegations. The former American naval facility, which is frequently visited by American ships, is also a popular Filipino tourist destination for beachgoers.