WASHINGTON (Reuters) - The United States signaled on Sunday that it and its partners could give as much financial support as Ukraine needs to get the crisis-hit country's economy back on track.

U.S. Treasury Secretary Jack Lew, who has urged Kiev to seek assistance from the International Monetary Fund, said Washington could lend a hand either through bilateral programs or larger international institutions.

"The United States is prepared to work with its bilateral and multilateral partners to provide as much support as Ukraine needs," Lew told a conference.

He said Washington was monitoring the situation in Ukraine with "grave concern" after Russia's intervention in Ukraine's Crimea region.

Lew said Ukraine would have to implement economic reforms for the United States to support any aid packages for Kiev.