April 14 (Reuters) - Ecuador's international bonds rallied sharply on Monday, rising 10 to 17 cents each in price after business heir and incumbent Daniel Noboa won a presidential runoff by a wider-than-expected margin.

Noboa, the heir to his father's vast business fortune, defeated leftist Luisa Gonzalez with around 56% of the vote. After ending neck-and-neck in the first round of voting, Sunday's election was expected to be a toss-up. Gonzalez claimed without offering proof that "grotesque" electoral fraud was at play.

Ecuador's bond maturing in 2040 was up over 10 cents, last trading at 49.5 cents on the dollar, according to LSEG data.

"The stunning result ensures policy continuity, the extension of the (IMF program), and continued progress on fiscal consolidation," wrote Geronimo Mansutti, senior LatAm credit analyst at Tellimer, in a client note on Monday.

"Encouragingly, Noboa's campaign avoided major new spending pledges or sweeping tax cuts, easing the path towards further consolidation."

Noboa, 37, has been president since November 2023 after beating Gonzalez in a snap election to finish out his predecessor's term.

Ecuador's international bonds rose 70% at the index level in 2024, with policy changes helping secure a program with the International Monetary Fund announced mid-year.

Bonds had fallen after Noboa, seen with a shot at reelection in the first-round vote in February, won by the thinnest of margins and Gonzalez's close second place pushed forward the possibility of a return of socialist policies.

"Riding the coattails of his bolstered political capital, Noboa's ADN (party) should have ample margin to attract support from the other political parties in a much more polarized legislature, with a greater capacity to push his reform agenda," JPMorgan's Ben Ramsey wrote in a note on Monday. (Reporting by Rodrigo Campos and Johann M Cherian; Editing by Hugh Lawson, Emelia Sithole-Matarise and Leslie Adler)