WASHINGTON — President Barack Obama sent a report to Congress Wednesday insisting that he did not exceed his powers in ordering US military action in Libya.

Officials said that the 30-page report justifies US action in the mission to protect civilians and target the forces of Moamer Kadhafi and contains a detailed legal analysis showing Washington's role is permitted under US law.

It came amid rising criticism among even some of Obama's allies on the operation and Obama's authority to wage it, along with questions about the ultimate US goal in Libya and the mounting cost of the action.

But senior Obama aides said the US role in the NATO-led operation, now largely confided to a support mission, did not rise to the level of warfare that the Act says must be endorsed by lawmakers under the 1973 War Powers Act.

"We are not engaged in any of the activities that typically over the years in war powers analysis has been considered to constitute hostilities within the meaning of the statute," a senior administration official said.

"We are not engaged in sustained fighting, there has been no exchange of fire with hostile forces, we don't have troops on the ground, we don't risk casualties to those troops," the official said on condition of anonymity.

"Within the precedents of a war powers analysis... we are confident we are operating consistent with the resolution."

The report was rushed to Capitol Hill after House Speaker John Boehner sent a scathing letter to the president warning that US operations would be illegal come Sunday because they lacked formal congressional approval.

Boehner cited the War Powers Act, that gives presidents 60 days to get authorization for a military deployment and, failing that, sets a further 30 days to withdraw them from harm's way.