Sept 17 (Reuters) - Yemenis took to boats in the Red Sea to escape fighting between Iran-backed Houthi fighters and Saudi-backed forces, as the spreading Middle East war created new threats to global oil supplies.

"The sea was wavy. The children were getting seasick; everyone... is not used to the sea," said Ahmad Hassan, 70, who reached Africa in a crowded boat and gave an interview to the International Organization for Migration.

He had fled his village after Houthi fighters arrived and it came under airstrikes: "The longer we stayed, the worse things got, the shops closed and there was no more food to buy."

The IOM says more than 100,000 Yemenis have been displaced by the latest fighting, mostly within Yemen.

Houthi-controlled television reported fresh Saudi air strikes on Thursday in Hajjah province close to the Saudi border near the Red Sea coast, and the vicinity of Taiz further inland to the south.

The Houthis, who have seized Yemen's entire Red Sea coast since last week in a lightning advance, say the Saudi Air Force has conducted hundreds of airstrikes in recent days. They in turn have fired missiles and drones at targets across the border.

On Wednesday, the Houthis said they had shot down a Saudi F-15 fighter jet. Video they released overnight showed fighters shouting "Allahu Akbar" in the charred wreckage of a crash site and holding up a piece of a military aircraft wing bearing Saudi insignia.

TRUMP HOPES WAR WILL END SOON

The spread of the Middle East war to Yemen and Saudi Arabia threatens to worsen the global energy supply shortage caused since the United States and Israel attacked Iran in February.

Global crude prices have hovered this week between $100 and $110 a barrel, the highest levels since May, and the cost of fuel for consumers and industry has risen even more sharply. The average retail price of diesel in the United States set a new all-time record on Thursday just shy of $6.40 a gallon.

U.S. President Donald Trump has so far rebuffed pleas from the Saudis for military support fighting the Houthis, who agreed a ceasefire with the United States last year after Washington bombed the group for two months.

"Well, hopefully we are towards the end of the war," Trump told reporters on Wednesday. He said the Iranians "want to make a deal. We'll see how that works out."

No negotiations between the United States and Iran to end the war have been held since an interim agreement reached in June collapsed within weeks.

The U.S. Navy is trying to guide ships through the Strait of Hormuz, the outlet to the Gulf along Iran's coast, where a fifth of global oil and liquefied natural gas passed before the war, and is also imposing a blockade of Iranian ports.

Iran says the strait is closed and will remain shut until Washington lifts the blockade. It is seeking an agreement with neighbouring Gulf states that would let it collect fees from ships passing through the strait.

War in Yemen and attacks on Saudi Arabia have jeopardised the main alternative route for Gulf oil, with the Houthis capturing the Red Sea coast and islands inside the Bab el-Mandeb, or "Gate of Tears", the strait at its mouth.

Saudi Arabia's East-West Pipeline, which allowed it to pump oil across the Arabian Peninsula and ship it from the Red Sea, has been shut since it was struck last week in an attack Riyadh said came from Iraq, where Iran-backed militias also operate.

(Reporting by Reuters bureauxWriting by Peter Graff; Editing by Alexandra Hudson)