Several groups claimed that Zamboanga City in the southern Philippines is like the "new Afghanistan" with the recent visit of U.S. military advisers who mapped up training and assistance to Philippine government troopers which are battling the hostage-taking Abu Sayyaf, believed to have active links with Saudi-born Osama bin Laden and his Al Qaida network.

Several groups staunchly opposed the deployment of 19 Delta Force elements in Zamboanga, adding this would further cause human rights violations against the people in Mindanao.

"The Delta Force are among the United States' ruthless killing machines. How could Arroyo allow for these cold-blooded mercenaries to use Mindanao as their playground for military activities," said Congressman Crispin Beltran in a statement that reached Jolo.

Many rights groups expressed anxiety over increased U.S. assistance in the Philippines, following President Gloria Arroyo's request for military assistance against terrorists in Mindanao.

Arroyo was the first of the Association of Southeast Asian Nations (Asean) to support U.S. President George W. Bush after the terror attacks in the U.S. on September 11.

The 15-member U.S. contingent arrived in Zamboanga City on Friday, but top government officials said they were not tasked in the rescue operations for the release of American missionaries Martin and Gracia Burnham, from nearby Basilan island.