MANILA, Philippines ? Senators and congressmen began grilling Palace and security officials on the basis for the declaration of martial law in Maguindanao province.

Executive Secretary Eduardo Ermita stressed that the issuance of Proclamation 1959 on the province was a ?faithful exercise? of President Gloria Macapagal-Arroyo?s ?prime duty to preserve and defend the constitution.?

Showing a slideshow of photos in the plenary, Police Inspector Andres Caro, Philippine National Police operation director, reiterated the details of the November 23 massacre in Maguindanao that prompted the government to place it under martial rule.

Senator Benigno ?Noynoy? Aquino III, the first interpellator, questioned the basis for Malacanang?s decision to declare martial law in the province, when it said earlier that it was not needed.

Interior and Local Government Secretary Ronaldo Puno, meanwhile, replied that verified reports of Ampatuan supporters are amassing themselves in Maguindanao necessitated greater control of the province.

Ermita said martial law was needed because ?the situation had to be controlled to account for perpetrators, allow prosecutors to do their job, and at the same time, be able to gather enough evidence.?

Questioned anew by Aquino about the President?s extraordinary powers during martial law, Justice Secretary Agnes Devanadera said a state of emergency was not sufficient since it merely empowers the President to call on the armed forces and the police to take control of a particular area and quell lawlessness.

Devanadera said martial law and the suspension of the writ of habeas corpus allows the President to address rebellion and invasion.

She said the reports of the Armed Forces of the Philippines showed that the Ampatuans were linked to the massing up of armed groups.

?Because of the report that those who were originally organizing, originally recruited to defend the public and the people, there are the same people who have now been transformed into a private army. They now follow not the rule of the Republic but their leaders, the Ampatuans,? Devanadera said.