WASHINGTON (Reuters) - The U.S. intelligence community assesses with varying degrees of confidence that the Syrian regime used chemical weapons on a small scale, the White House said on Thursday, adding however that such assessments were not enough and that "credible and corroborated" facts were needed.

"Given the stakes involved, and what we have learned from our own recent experiences, intelligence assessments alone are not sufficient - only credible and corroborated facts that provide us with some degree of certainty will guide our decision-making," Miguel Rodriguez, White House director of the office of legislative affairs, said in a letter to lawmakers.

(Reporting Roberta Rampton and Phil Stewart; Editing by Vicki Allen)