President Gloria Arroyo has stressed that Osama bin Laden was not the reason why she has allowed the U.S.-Philippine war games.

"There is no room for imported terrorists," Arroyo said, reacting to reports that bin Laden could be hiding in Abu Sayyaf strongholds of Jolo, Basilan or Tawi-Tawi.

"He cannot hide in Basilan when all those who claimed to be his friends are now on the run or are holed up," said Arroyo.

"We never invoked Osama bin Laden's presence to justify the presence of American groups. We invoked the Visiting Forces Agreement."

Arroyo said she will tour Zamboanga City later this month, but did not say if she will visit Filipino and the U.S. troops in Basilan, now home to some 32 American soldiers to be joined by 128 others on Monday.

Some 660 American and 3,800 Filipino soldiers are taking part in the exercise, set to begin in Basilan in the next few days and will last until July.

The U.S. President George W. Bush has praised Arroyo for her new foreign policy. By phone Bush told Arroyo the U.S. is grateful for her cooperation in the war against terrorism.

"He specifically noted how President Arroyo has made every effort to secure the release of two Americans who have been held hostage in the southern Philippines," the presidential palace quoted U.S. presidential spokesman Ari Fleischer as saying.

"The president also emphasised his determination to see our current training mission to a successful conclusion," Fleischer said.

The U.S. presence in Mindanao is the largest American military deployment abroad since the Afghan campaign against the Taliban.

Reporters were banned from covering the movement of the U.S. and Philippine troops for security reasons, officials said.

It could be the start of ambushes, close combat, assassinations and savage clashes with Abu Sayyaf fighters.

"This is assistance. This is training," said Gen. Richard Myers, chairman of the joint chiefs of staff.