Filipino authorities on Monday arrested three men who were reportedly plotting to set off bombs at various locations in the capital city of Manila. The men are to be charged with possession of explosive materials, a non-bailable offense.

The men were preparing to target Ninoy Aquino International Airport, the Chinese embassy and at least one of the city's biggest malls, reports said, adding that the arrests were made after authorities found explosives in a van at the airport's parking lot.

“Apparently this is a misguided group. They claim to be defenders of the Filipino people and consider China and (Filipino-Chinese) oligarch taipans' monopolistic business practices and illegal mining as enemies," Justice Secretary Leila de Lima said, according to Agence France-Presse, or AFP, adding: “They want this administration to espouse a tougher stance in this dispute with China.”

The police were reportedly tipped off by an anonymous person who said the men were planning to set off a bomb in an airport restroom as well as at three malls owned by ethnic Chinese. One of the malls the men planned to attack was reportedly owned by Henry Sy, the country’s richest man, who was born in China. Another plan included blowing up a building owned by a power plant company that allegedly employed illegal Chinese workers.

Although the men are to be charged with possession of explosive materials, a non-bailable offense, Associated Press, or AP, reported that they were caught carrying firecrackers, prompting military personnel to play down their offense and call them “pranksters.”

"I don't think it's a terror attack because these were just firecrackers," Military Chief of Staff Gen. Gregorio Pio Catapang said, according to AP.

However, de Lima sought to take a more serious view of the alleged plans, and said: “We want to know how big this group is, what is their capacity really to create all this havoc, and what is their real agenda," according to AFP, adding: "Are they on their own or are there (people) behind them? We will investigate all these."

De Lima also reportedly added that the leader of the group belonged to a secret fraternity of police and militia forces who have been trying to orchestrate a coup since the 1980s.

The Philippines is involved in a territorial dispute with China over parts of the South China Sea, and last year, filed a case at The Hague against China's actions in the region. In June, the Philippines said that it will appeal to the Association of Southeast Asian Nations, or ASEAN, to put a stop to the construction of a Chinese school on an island claimed by both countries.