A cardboard sign identifying the man as a "Chinese drug lord" was found on the body, police said.
"Chinese drug lords are no longer allowed here in the Philippines. We will exterminate you," the sign said in Filipino, indicating that the man was executed by vigilantes.
Investigators are still trying to determine the victim’s identity, said Cavite police chief Senior Superintendent Roberto Rosales.
Rosales said a spent rifle bullet shell was found near the body but they suspect that the victim was killed somewhere else. The man was shot several times, he added.
However, local residents living near the crime scene told investigators that they heard gunshots at around 3 a.m. yesterday, Rosales said.
The man was found gagged with duct tape, his hands also tied with duct tape as well as his right ankle, he said.
Rosales did not rule out the possibility that vigilantes were responsible. "A group may have been formed to help police in curbing drug trafficking and addiction in the province," he said.
Vigilantes have been blamed in the past for killing suspected drug traffickers, often found with cardboard signs around their necks to serve as a warning to offenders.
However, police, frustrated by the agonizingly slow justice system, have also been suspected in the past of carrying out executions.
President Arroyo has recently launched an intensified campaign against illegal drugs and has ordered the military to assist the Philippine Drug Enforcement Agency, the office spearheading the crackdown.
Police say many crimes have been sparked by drugs, the most abused of which is methamphetamine hydrochloride, commonly known as shabu.
Police say much of the shabu sold in the Philippines comes from China. Most of the dozen foreign drug syndicates operating in the Philippines are Chinese, authorities earlier said.
Mrs. Arroyo warned that drug traffickers and terrorist groups have formed an "alliance" in strife-torn Mindanao, adding "it is time we confronted this complex and deadly conspiracy."
"There are indications of an alliance between terrorist groups and illegal drug syndicates in Mindanao," she said in a speech at a conference on illegal drugs in Marawi City on Wednesday.
She did not identify the groups nor the kind of gangs allegedly involved in the alliance.