WASHINGTON, Feb 14 (Reuters) - The United States has told Congress and allies in Europe about new intelligence related to Russian nuclear capabilities that could pose an international threat, a source briefed on the matter told Reuters on Wednesday.

The new capabilities, related to Russian attempts to develop a space-based weapon, do not pose an urgent threat to the United States, the source said.

The intelligence came to light after Representative Mike Turner, Republican chair of the U.S. House of Representatives intelligence committee, issued an unusual and cryptic statement on Wednesday warning of a "serious national security threat."

Sources later said the warning was related to Russian capabilities in space, related to satellites. One of the sources said the issue is serious, but is not related to an active capability nor should it be a cause for panic.

"I am requesting that President Biden declassify all information relating to this threat so that Congress, the Administration, and our allies can openly discuss the actions necessary to respond to this threat," Turner said in the statement, providing no further information.

Citing a current and a former U.S. official, the New York Times reported earlier that the new intelligence was related to Russia’s attempts to develop a space-based anti-satellite nuclear weapon. ABC News reported earlier that the intelligence had to do with such a capability. Current and former officials said the nuclear weapon was not in orbit.

Turner's statement was released in the midst of debate in Congress over how the United States should be dealing with global threats from Russia and other rivals, with security hawks urging greater global involvement and some lawmakers most closely allied with Republican former President Donald Trump advocating for a more isolationist "America First" approach to world affairs.

Turner recently returned from leading a bipartisan congressional delegation to Ukraine, after which he warned fellow lawmakers that time was running out for Ukraine in its fight against Russian invaders.

The Biden administration has been ramping up its criticism of House Republicans for possibly blocking a $95 billion bill passed by the Senate that would supply aid to Ukraine, Israel and Taiwan. Supporters of the bill argue that a major reason for the United States to back the government in Kyiv is to push back against threats from Russia that extend beyond Ukraine.