BOGOTA, June 8 (Reuters) - Colombia's President Gustavo Petro on Saturday said the country, which is reported to be Israel's biggest supplier of coal, will suspend exports of the fuel source to Israel over its assault on the Gaza Strip.

Petro, a leftist, cut diplomatic ties with Israel in May and has strongly criticized Israeli Prime Minister Benjamin Netanyahu. In a post on social media platform X, he said coal exports would be halted "until the genocide is stopped," referring to Palestinian deaths in the conflict.

Israel denies accusations that its war violates the international genocide convention.

The measure will take effect in five days, according to a Colombian government decree, which said coal is used by Israel as an energy source to make weapons and other military goods.

"Colombia believes that the military operations against the Palestinian people represent a transgression of a peremptory norm of international law," the document said.

According to the American Journal of Transportation, Colombia is the biggest supplier of coal to Israel, representing more than half of its imports.

Israel has relied on coal for 20% of its electricity generation but that is expected to drop to 3%, and it has other coal sources, the journal said.

Colombia's private mining association

has said such a ban would violate international agreements and put market confidence and foreign investment at risk.

Colombia is the world's fifth largest coal producer, with Drummond and Glencore among its major miners. The country sent 56.7 million metric tons of coal abroad last year, including 3 million tons to Israel, about 5.4% of total exports, according to government data. (Reporting by Julia Symmes Cobb and Daina Beth Solomon; Editing by Cynthia Osterman)