The "bullet scam" allegedly sees bullets dropped into the luggage of passengers as they go through security at the country's main airport.
Passengers are then required to pay a fine or face being charged with illegal possession of ammunition.
An overseas Filipino worker and Japanese tourist are the latest to complain.
"This is becoming an international embarrassment", said Sherwin Gatchalian, vice-chairman of the tourism committee in the House of Representatives.
Senator Ralph Recto stressed the need for intervention from authorities, adding: "There is no working system that is guarding the guards."
Gloria Ortinez - an overseas Filipino worker - was stopped from flying to Hong Kong after a bullet was found in her hand luggage at the Ninoy Aquino International Airport.
Ortinez denied the bullet was hers, saying she would never carry one because of Hong Kong's strict security laws.
Office of Transportation Security (OTS) personnel released her after several days in police detention.
Japanese tourist Kazunobu Sakamoto was found with two bullets in his luggage and arrested after failing to show documents authorising him to carry ammunition.
The reports have caused outrage, with locals criticising airport authorities. Mr Gatchalian condemned OTS staff, saying they were "not afraid to prey on foreigners".
Some of the passengers detained were released after the bullets were found to be blanks, while others were taken to court for refusing to pay fines.
Surveillance at the airport has been stepped up since the complaints began and an investigation has been launched into the personnel accused of involvement.
Philippine legislators have called for an investigation into an alleged scam against passengers at Manila airport.