President Barack Obama does not need congressional approval for the US to continue its role in the Nato-led Libya mission, the White House has said.

白宫表示，奥巴马总统不需要通过议会的批准即可继续维持美国在北约领导的利比亚行动中的地位。

In a 32-page document, the White House said the president already had legal authority to order forces into Libya.

A Vietnam War-era law states Congress must authorise participation¹ in hostilities² longer than 60 days.

Members of Congress have accused Mr Obama of violating that law since 20 May, when the 60-day deadline ended.

'Limited nature'

In the report delivered to Congress on Wednesday, the White House argues that US forces involved in the Nato campaign are merely playing a supporting role.

That role, the White House says, does not match the definition of "hostilities" as described under a 1973 law that constrains³（驱使，强迫） the US president's ability to wage military conflict.

"The president is of the view that the current US military operations in Libya are consistent（符合，一致） with the War Powers Resolution and do not under that law require further congressional authorization," the White House wrote.

"US military operations are distinct from the kind of 'hostilities' contemplated⁴（计划，深思） by the resolution's 60-day termination provision," it added.

The US role in Libya involves helping⁵ Nato aircraft with refuelling operations and assisting with intelligence-gathering, the White House says.

The Obama administration insists that the US is not engaged in sustained fighting or "active exchanges of fire with hostile forces" that put US troops at risk.

Under the US constitution, the power to declare war lies with Congress.

If the president orders the US military into a conflict without an explicit⁶（明确的，清楚的） declaration of war, the War Powers Resolution requires him to seek authorisation from Congress within 60 days or to end US involvement in the conflict.

The law allows the president to extend the period before going to congress for another 30 days.