Senator Ronald "Bato" dela Rosa has disclosed recently that he was given a "rock-solid" assurance by President Ferdinand Marcos Jr. that the International Criminal Court investigators will not be allowed to enter the country to probe the former administration's war on drugs campaign.

Dela Rosa said he received Marcos' assurance during a dinner meeting in Malacañang in November last year, stressing that he will hold onto the President's assurance.

The senator also echoed Marcos' earlier remarks "that any unauthorized investigation by foreign entities in the Philippines is an encroachment of the country's sovereignty" as he urged the authorities to "verify and confirm" the alleged entry of ICC investigators into the country.

The lawmaker said the government should ensure the country's position regarding ICC intrusion "must be upheld."

"The government's position should be maintained and it should be felt on the ground. Kung ang official position of the government is not to entertain them," Dela Rosa said.

He also cited former Senator Juan Ponce Enrile's earlier statement that any intruders to the country "can be arrested."

Should the ICC probers insist on unauthorized investigations in the Philippines, Dela Rosa said the Department of Justice, through the Bureau of Immigration, must declare the ICC probers as "undesirable aliens" should they insist on unauthorized investigations in the Philippines.

It must be followed by an immediate deportation, he added.

Dela Rosa recalled Marcos' previous remarks — which he kept as a "personal promise" — on defending the sovereignty of the Philippines.