By Joshua McElwee

ROME, April 3 (Reuters) - Pope Leo led a candle-lit service with thousands of Catholics inside Rome's famed Colosseum on Friday evening that featured prayers for war orphans and deported immigrant children, and a warning to world leaders that their decisions will be judged by God one day.

The pope, who has emerged as an outspoken critic of the Iran war, listened as an evocative set of spiritual meditations was read aloud inside the ancient amphitheatre to observe Good Friday, the day Christians mark Jesus' death by crucifixion.

April 3 (Reuters) - An unnamed source told Iran's semi-official Fars news agency on Friday that Tehran had rejected a U.S. proposal for a 48-hour ceasefire.

The source said the proposal was made on Wednesday through another country, which was not named.

There was no immediate comment or confirmation from the U.S.

(Reporting by Reuters; Editing by Mark Porter)

By Maya Gebeily and Ahmed Tolba

BEIRUT, April 3 (Reuters) - Israel pounded Beirut with airstrikes on Friday that the military said had targeted militant "infrastructure" in Lebanon's capital, as the U.S. warned that Iran may target universities in the country as the Middle East war rages.

Israel has invaded southern Lebanon and pledged to raze all Lebanese villages in the border area in a fight against Iran-backed Hezbollah militants that has become the most violent spillover of the U.S.-Israeli war with Iran.

One French- and another Japanese-owned vessel are among a handful of vessels to have crossed the war-torn Strait of Hormuz, maritime tracking data showed Friday.

The passage, a vital maritime route for oil and liquified natural gas, has been virtually blocked by Iran since the start of the war.

But both ships made the crossing on Thursday, according to ship tracking company Marine Traffic's website.

By Kentaro Okasaka and Kantaro Komiya

TOKYO/OSLO, April 3 (Reuters) - Three Omani-operated tankers, a French-owned container ship and a Japanese-owned gas carrier have crossed the Strait of Hormuz since Thursday, shipping data showed, reflecting Iran's policy to allow passage for vessels it deems friendly.

Iran initially shut the Strait - a route for about a fifth of global oil and LNG flows - after U.S. and Israeli airstrikes on Iran at the end of February led to a widening conflict. Later, it said it would permit transits by ships with no U.S. or Israeli links.

As he wages war on Iran, President Donald Trump was joined in the Oval Office by Christian pastors. Solemnly, some placed their hands on his shoulder or forearm. They offered their blessings.

In a war against a country led by Shia Muslim clerics, the United States -- which has a constitutional separation between church and state -- is also invoking religion, with some Trump officials casting it as almost a divine mission.

Here are the latest developments in the Middle East war:

- Israel strikes Beirut -

The Israeli military said Saturday it had begun striking "Hezbollah infrastructure sites" in Lebanon's capital Beirut.

An AFP journalist heard two loud explosions in the capital within a half-hour period early Saturday and saw smoke billowing from one of them.

Local media reported two airstrikes on the southern suburbs.

- Missiles fired toward Israel -

The Israeli army said its air defences responded to missiles fired from Iran, which medics reported wounded one person.

By Phil Stewart

WASHINGTON, April 3 (Reuters) - A U.S. fighter jet has been shot down over Iran and a search-and-rescue operation is underway for any survivors, two U.S. officials told Reuters on Friday, in the first such known incident since the war began nearly five weeks ago.

The Pentagon and U.S. Central Command did not respond to requests for comment.

The prospect of U.S. pilots being alive and on the run inside Iran raises the stakes for the United States in a conflict that has struggled to win popular support among Americans, according to opinion polls.

MOSCOW, April 3 (Reuters) - Russian President Vladimir Putin has held a phone call with Turkish President Tayyip Erdogan, the Kremlin said on Friday.

Putin and Erdogan discussed the situation in the Middle East, the Kremlin added.

(Reporting by Ksenia Orlova; Writing by Anna Peverieri; Editing by Kevin Liffey)

ROME, April 3 (Reuters) - Italian Prime Minister Giorgia Meloni flew to Saudi Arabia on Friday for a previously unannounced trip that will also include meetings in Qatar and the United Arab Emirates, government sources said.

The sources said the visit would reaffirm Italy's support for the three nations in the face of Iranian attacks on their territories, and was also aimed at bolstering Italy's national energy security through closer engagement with Gulf producers.