(Sharecast News) - Iran's new supreme leader Mojtaba Khamenei said on Thursday that the Strait of Hormuz should stay closed as a way to keep up pressure on the West.

In the first public statement since his appointment, he also said that all US bases in the Middle East should be closed and would be attacked.

In comments read out on Iranian state media, Mojtaba - who succeeds his father Ayatollah Ali Khamenei - said the vital Strait of Hormuz should remain closed as a "tool to pressure the enemy".

"Iran will not refrain from avenging the blood of its martyrs," he said, adding that Iran will seek compensation from enemies "or destroy their assets accordingly". Khamenei specifically mentioned the Minab school attack, in which at least 165 people were killed, mainly children.

Oil prices took another leg higher following the comments and by 1350 GMT Brent crude was up 7.8% at $99.11 a barrel, while West Texas Intermediate was 7.9% higher at $94.15.

Prices had spiked above $101 a barrel overnight, before falling back, despite countries around the world pledging to release crude reserves, as hostilities intensified in the Middle East.

The International Energy Agency said on Wednesday that its 32 members had agreed to release an unprecedented 400m barrels of oil, to help curb the economic fallout from the war.

Prices initially softened in response, but overnight they once again raced higher, after three more vessels were hit in the Gulf, two in Iraqi waters and another near Dubai. A fuel facility in Bahrain and an Italian military base in Iraq were also hit.

Around a fifth of the world's oil supply is transported through the narrow Strait of Hormuz between Iran and Saudi Arabia. It is now deemed too dangerous to use, and shipping traffic has ground to a near-halt.

US president Donald Trump has been vocal about his disappointment over the selection of Khamenei as Iran's new supreme leader, saying on Monday that he was "not happy" with the choice.

Speaking to Axios last Thursday, he also said Khamenei's son was "a lightweight". "I have to be involved in the appointment, like with Delcy [Rodriguez] in Venezuela," Trump said.