MANILA, Philippines – (UPDATE) Lawmakers are calling for an immediate investigation into the continued presence of American troops in conflict areas in Mindanao that they fear could worsen the situation in the south.

Opposition Senator Panfilo “Ping” Lacson said he was baffled by the frequent visits to the region of US Ambassador to the Philippines Kristie Kenney and cited the need to investigate reports of overstaying American troops.

Lacson said this was a “good issue” to investigate, citing the notable interest of the US in Mindanao and its participation in the aborted memorandum of agreement on ancestral domain between the Philippine government and the Moro Islamic Liberation Front.

“It’s a good issue to be investigated by the Senate defense committee. So why not para lang makita natin kung may [so that we can see whether there is a] violation ng [of the] VFA [Visiting Forces Agreement] at violation sa pinirmahan natin [and a violation of what we signed] with the Americans,” he told reporters on Monday.

“If you saw the guest list sa [in the] aborted signing ng [of the] MOA-AD, magugulat ka sa personalities doon [you’ll be surprised at the personalities you will find there],” he said.

“Bakit, kung bibilangin mo ang bisita ni [Why, if you will count the number of visits by] Kenney, out of 365 days at least 120 days na sa Mindanao siya [she is in Mindanao]. Bakit ganun kalaki ang interest ng US sa Mindanao [Why is the US very interested in Mindanao]? Dahil ba napakayaman sa resources ng Mindanao at kailangan hiwalay sa Pilipinas nang sa ganoon ang foreign interest ay papasok doon [Is it because Mindanao is rich in resources and there is a need to separate the region from the Philippines so that foreign interest could enter]?” he said.

But Senator Miriam Defensor-Santiago, co-chairperson of the oversight committee on the VFA, would rather leave the issue to the executive to find out whether the US has violated the VFA.

“Because monitoring the claim of the US that they have not violated the VFA in the sense that they have not set up permanent bases or permanent personnel or any bases station in Mindanao, since that’s executive in nature, we’re going to wait for the report of the VFA commission,” Santiago said.

“This can’t be resolved in one or two days by a Senate panel so we should to wait for the executive commission to make a report, then we will summon the chair of the executive commission to report on the Senate and we shall determine for ourselves if his report his accurate or not,” she said.

If the report will show that the VFA had been violated, then Santiago said they would bring the issue to the Department of Foreign Affairs.

At the House of Representatives, Gabriela Representative Liza Maza filed House Resolution 772 calling for an immediate "inquiry into the constitutionality and legality of the continuing presence and involvement of the United States military forces in Philippine military activities, particularly in conflict areas in Mindanao."

The resolution cited reports that four American soldiers joined local troops search for unexploded bombs in Baliki, Midsayap town in North Cotabato province even as firefights were going on between government forces and MILF rebels.

In a press conference Monday, Bayan Muna (People First) Representative Satur Ocampo also noted perceptions the Americans, who are here as allowed by the VFA, were looking toward a permanent military when the treaty limited their stay at any one time to only three to six months.

"We want to call for an immediate investigation on this and fault the government when there is supposed to be the Visiting Forces Agreement Commission that should be monitoring the movement of US troops," said Ocampo, as he urged the House committees on defense and foreign affairs to look into the reports.

Akbayan Representative Risa Hontiveros also said the reported participation of American soldiers in continuing military offensives against the MILF would remind the Moro people of the American troops' role "in the oppression of the Bangsamoro [Moro nation]" decades ago.

"The reported participation of US soldiers in the battlefield is not only constitutional and illegal. It is very reminiscent of the 'pacification campaigns' waged by American soldiers decades ago that led to the killings of Moros," Hontiveros said.

Philippine and American officials have denied the foreign troops’ participation in local military operations and said all the activities of the US military were in accordance with existing agreements.