(Recasts first paragraph, adds quotes from McCain, Smith)
WASHINGTON, Aug 31 (Reuters) - U.S. Democratic and Republican lawmakers on Sunday urged Washington to arm the Ukrainian government, saying it needed help to repel what they called Russia's invasion of the country.
Senator Robert Menendez, who heads the Senate Foreign Relations Committee, told CNN the United States, European Union and NATO should work together to arm Kiev, which has been fighting Russian-backed rebels in eastern Ukraine for months.
"We ... should be providing the Ukrainians with the types of defensive weapons that will impose a cost upon (Russian President Vladimir) Putin for further aggression," the New Jersey Democrat told the "State of the Union" program from Kiev.
Asked whether the Obama administration is considering such a move, Menendez said: "I think that may very well be on the table right now. These are changed circumstances."
President Barack Obama last week ruled out U.S. military action over Ukraine and called for a diplomatic solution.
The Obama administration has stopped short of calling Moscow's intensified support for separatist forces in eastern Ukraine an invasion, and has said sanctions are the most effective tool in dealing with Russia's actions in Ukraine.
Republican Senator John McCain from Arizona said he backed sanctions but Ukraine also needed intelligence data and weapons.
"For God's sake, can't we help these people defend themselves? This is not an incursion. This is an invasion," McCain told CBS's "Face the Nation" program. He said Russia could threaten Moldova and the Baltics if it was not stopped.
Representative Mike Rogers, the Republican who heads the House Intelligence Committee, said the United States and Europe needed to provide strategic help to Ukraine now to halt what he called Russia's increasingly aggressive actions.
"If we don't provide 'small and effective' now, you're going to get very big and very ugly later," Rogers said on "Fox News Sunday." "Now is the opportunity to make that decision and ... not make the same mistake the president made in Syria."
Putin called on Sunday for immediate talks on "statehood" for southern and eastern Ukraine, although his spokesman said this did not mean Moscow now endorsed rebel calls for independence for territory they have seized.
Menendez called for stepping up sanctions on Russia, saying that the United States should impose sectoral sanctions on Russian companies in the financial and energy industries.
Kiev and its allies in Europe and the United States, who have imposed sanctions against Russia over its role in Ukraine, say a new separatist offensive in its east has been backed by armored columns of more than 1,000 Russian troops.
"This is a direct invasion by Russia. It's not rebels, it's Russian soldiers," Menendez said.
Representative Adam Smith, the top Democrat on the House Armed Services Committee, told the CBS program Washington should be more "forceful" in its support for the Ukrainian government.
Smith's spokesman said he supported sending arms, but wanted more details about the types of weapons that would be sent. (Reporting by Michael Flaherty and Andrea Shalal; Editing by Mohammad Zargham and Andrea Ricci)