WASHINGTON (CNN) -- The United States is sending an additional $12 million in humanitarian aid to Syria, the White House announced Thursday, warning of a "dire and rapidly deteriorating" situation inside the country.

Citing U.N. estimates, the White House said up to 1.5 million Syrians are in need of aid, including more than 130,000 who have fled the country amid a widespread uprising against President Bashar al-Assad.

"With these additional funds, the United States is now providing over $76 million in assistance for food, water, medical supplies, clothing, hygiene kits, and other humanitarian relief to those most urgently in need," the White House said. The statement repeated U.S. calls for al-Assad to step down and "enable a peaceful political transition to a government that is responsive to the aspirations of the Syrian people."

The move comes a day after U.S. officials told CNN that President Barack Obama had signed a directive authorizing covert, nonlethal U.S. support for Syrian rebel fighters by the CIA and other agencies. It was unclear exactly what the secret order, referred to as an intelligence "finding," authorized and when it was signed, but the sources said it was within the past several months.

The Obama administration had said it would step up its assistance to the opposition after last month's failure by the U.N. Security Council to agree on tougher sanctions against the Assad regime. But the administration has ruled out arming the rebels for now, providing only nonlethal assistance such as communications equipment.

Syrian state TV reacted to American news reporting about the directive, saying Obama has decided to "support terrorists."

U.S. officials have told CNN that Washington is cooperating with countries that are arming the rebels, including Saudi Arabia and Qatar, to help find groups worthy of aid. Diplomatic sources have also said the United States is providing intelligence on Syrian troop movements, which is then passed to rebel groups.