* Trump gives Iran 48-hour ultimatum to reopen Hormuz

* Trump threatens to obliterate Iranian power plants

* Iran says to respond with attacks on Gulf energy,

desalination facilities

* Oil closed near 4-year high on Friday

(Updates with settlement prices)

LONDON/SINGAPORE, March 22 (Reuters) - Oil prices look

set to rise further on Monday, having closed before the weekend

at their highest in nearly four years, after U.S. and Iranian

threats to target energy facilities, analysts said on Sunday.

U.S. President Donald Trump on Saturday threatened to

"obliterate" Iran's power plants if Tehran did not fully reopen

the Strait of Hormuz within 48 hours, a significant escalation

barely a day after he talked about "winding down" the war, now

in its fourth week.

Iran warned on Sunday it would attack U.S.-linked

infrastructure, including energy and desalination facilities in

the Gulf, if Trump carried out his threat.

On Friday, Brent futures for May settled up 3.26% at

$112.19 a barrel, the highest since July 2022.

"President Trump's threat has now placed a 48-hour ticking

time bomb of elevated uncertainty over markets," said IG market

analyst Tony Sycamore. If the ultimatum is not walked back, oil

prices will spike on Monday, he said.

"It clearly means more escalation which means higher oil

prices. Some are incorrectly thinking, however, that Iran may

cave," said Amrita Sen, founder of Energy Aspects. "Trump is

trying to show he can out-escalate and that way ends in scorched

earth for Gulf infrastructure."

Iran has attacked ports and refineries in Saudi Arabia,

Kuwait, Bahrain, the UAE and Qatar in retaliation for attacks on

its infrastructure. The closure of Hormuz resulted in a loss of

a full four days of global supply - or some 440 million barrels

- during the 22 days of the war so far.

Tehran has so far refrained from attacking large

desalination plants in Saudi and the UAE, which are responsible

for the water supply for millions of people.

Large scale damage to those facilities could make some

cities in the Gulf uninhabitable within weeks and force mass

evacuations and cascading power failures, according to the

Atlantic Council.

Brent gained about 8.8% last week, while the front-month WTI

settled down around 0.4% compared with last Friday's close.

WTI's discount to Brent hit its widest in 11 years on Wednesday.

Restoring supplies from the Middle East Gulf could take up

to six months, International Energy Agency chief Fatih Birol

told the Financial Times on Friday.

The Trump administration is considering plans to occupy or

blockade Iran's Kharg Island to pressure Iran to reopen the

Strait of Hormuz, Axios reported on Friday.