Released at the UN climate summit in Brazil, the analysis titled "Behind the Barrel" found that 25 countries were responsible for 323 shipments of crude and refined petroleum products totaling 21.2 million tonnes between November 1, 2023, and October 1, 2025.

Azerbaijan and Kazakhstan were by far the largest suppliers of crude, accounting for 70 percent of shipments.

Russia, Greece and the United States were the top providers of refined petroleum products -- with the US standing out as the sole supplier of JP-8, a jet-fuel blend designed for military aircraft.

"States risk becoming complicit in genocide under international law, under the Genocide Convention," Shady Khalil of Oil Change International told reporters.

"As world leaders convene at COP 30, 'Behind the Barrel' reveals the deadly links between fossil fuel suppliers and international conflict."

The group commissioned research firm Data Desk to conduct the analysis.

The conflict began in October 2023 when an attack by Islamist group Hamas killed 1,221 people in Israel, mostly civilians, according to an AFP tally based on official figures.

Israel's retaliatory campaign has since killed more than 69,000 Palestinians, according to Gaza's health ministry, whose data is deemed reliable by the United Nations.

Israel and Hamas agreed to a ceasefire in Gaza that has largely halted the war since October 10, though violent incidents continue to be reported, often with fatalities.

A UN Commission has concluded Israel has committed genocide in Gaza, and the International Court of Justice has ruled that Israel's continued presence in occupied Palestinian territory are unlawful.

Irene Pietropaoli, a senior fellow in business and human rights at the British Institute of International and Comparative Law, said in a statement that states were obliged to follow the ICJ's interim order directing them to "prevent and punish genocide."

"States must consider that their military or other assistance to Israel's military operations in Gaza may put them at risk of being complicit in genocide under the Genocide Convention," she said.

Asked by AFP whether it was important to differentiate between oil for civilian versus military use, Ana Sanchez Mera, coordinator for the Global Energy Embargo for Palestine who was part of a panel discussion on the topic, said "it is one system of settler colonial occupation."

She gave the example of Israel's electricity grid, which was partially powered by coal and connects both Israel and illegally occupied Palestinian lands.

In August 2024, Colombian President Gustavo Petro announced that the country had formally suspended coal exports to Israel.

While official data indicates Brazil last sent oil directly to Israel in March 2024, the head of the Rio de Janeiro Oil Workers Union has claimed Brazil may have rerouted shipments via Italy.