UPDATE 1-Ukraine's bonds slide as war worries overshadow US aid relief

(Updates prices in paragraph 3, adds analyst comments in paragraphs 6-7 and 11-12)

By Marc Jones and Libby George

LONDON, April 22 (Reuters) - Ukraine's government bonds fell on Monday as concern about the ongoing war and debt-restructuring overshadowed initial investor relief over the approval of a $61 billion U.S. aid package.

The U.S. House of Representatives passed the funding on Saturday, ending a six-month impasse during which Russia regained the upper hand in some of the key battlegrounds in the more than two year-old war.

Ukraine's main government bonds initially ticked higher but fell by as much as 1.64 cents by 1408 GMT. The 2028 maturity was trading at 29.23 cents on the dollar, its lowest since early March.

"It's great that the money is coming through, but I don't think it's a game-changer (for investors)," Paul McNamara, an investment director of emerging market debt at fund manager GAM, said.

"The big concern at the moment is that the military situation has tilted against it again, which is keeping everything in doubt."

Other investors echoed such concerns. Guillaume Tresca, senior emerging market strategist at Generali Investments, said that while the U.S. money "can be seen as a positive," it was marginal compared with longer-term concerns, including debt restructuring.

"We don't forecast any major impact on markets, excluding other factors which are more tied to political and military events," Tresca said.

Sources told Reuters over the weekend that Kyiv aimed to present a debt restructuring plan within the next two months, but investors are concerned it will be unable to do so if it is still engulfed in war.

A two-year debt payment freeze agreed shortly after the Russian invasion began in February 2022 will end in August, although it could be extended if both sides agree.

Most of Ukraine's bonds are trading at between a quarter and third of their original face value.

Minna Kuusisto, director and chief analyst with Danske Bank, said Russia still had the upper hand, despite the aid package, and investors were weighing the potential impact of Donald Trump's return to the White House if he were to win U.S. presidential elections in November.

"I think it's clear both Ukraine and Europe have to acknowledge they cannot rely on further support from the U.S. after this package," Kuusisto said.

(Reporting by Marc Jones and Libby George; editing by Barbara Lewis)