By Lili Bayer

BRUSSELS, April 23 (Reuters) - European Union leaders will discuss the bloc's mutual assistance clause at a summit in Cyprus on Thursday, as U.S. President Donald Trump's criticism of traditional allies raises concerns over his commitment to NATO at a time of growing insecurity.

The clause, contained in the treaty that underpins the EU, obliges countries to come to the aid of a fellow member if it comes under attack. But officials say there are currently no clear rules about how it should work in practice.

The latest developments in the Middle East war:

- Israel-Lebanon ceasefire extended -

The ceasefire between Israel and Lebanon will be extended for three weeks, US President Donald Trump announced Thursday during a meeting between Israeli and Lebanese ambassadors.

"I think there's a very good chance of having peace. I think it should be an easy one", Trump told reporters, adding that he plans to meet with top leadership from both countries in the next couple weeks.

- Hezbollah fires on northern Israel -

BRUSSELS, April 23 (Reuters) - Italy's deal to send migrants to Albania while their asylum claims are processed is compatible in principle with EU rules, an adviser to the bloc’s top court said on Thursday, offering a lifeline to a policy repeatedly challenged in the courts.

Prime Minister Giorgia Meloni welcomed the statement as a validation of a programme she had presented as a cornerstone of her tough approach to immigration.

Several other European countries have been considering it as a possible model, and watching its progress through the legal system.

ROME, April 23 (Reuters) - Italy is ready to deploy up to four vessels, including two minesweepers, as part of an international mission to clear the Strait of Hormuz, the navy's chief of staff said.

European leaders met in Paris last week to discuss a multinational effort to protect shipping through the strait, which was largely closed during the U.S.-Israel war against Iran.

BERLIN, April 23 (Reuters) - The son of the former Shah appealed to Western countries to join the war against Iran and criticised the decision of the German government not to meet him during his visit to Berlin on Thursday.

Reza Pahlavi, whose father was deposed in the revolution that brought Ayatollah Ruhollah Khomeini to power in 1979, accused Europe of standing by and allowing the Tehran government to continue the bloody repression of protests that killed thousands at the end of last year.

CAIRO/GAZA, April 23 (Reuters) - Israeli airstrikes killed at least four Palestinians in Gaza on Thursday, Palestinian health officials said.

One person was killed in a strike in southern Gaza's Khan Younis in which several others were wounded, local medics said. Israel's military said it had targeted militants transporting munitions, who it said had posed a threat to Israeli soldiers.

By Jonathan Saul, Renee Maltezou and Yannis Souliotis

LONDON/ATHENS, April 23 (Reuters) - Two container ships seized by Iran near the Strait of Hormuz with about 40 crew aboard have been taken toward the port of Bandar Abbas, sources said on Thursday, Tehran having vowed to retaliate after U.S. forces seized an Iranian vessel three days earlier.

Iran’s Islamic Revolutionary Guard Corps seized the ships on Wednesday, one operated by MSC, the world's biggest container shipping group, and according to three sources, the other chartered by the firm.

Reza Pahlavi, the son of Iran's ousted shah, argued Thursday that any negotiations with the clerical leadership in Tehran amount to "appeasement" and voiced hope that renewed street protests will topple it.

Pahlavi, 65, was speaking on a visit to Berlin, where he was greeted by some supporters but also bitter opponents -- with one activist splashing a red liquid on him before being detained by police.

By Panu Wongcha-um

BANGKOK, April 23 (Reuters) - More than 30 million people will be pushed back into poverty by the impacts of the Iran war including disruptions to fuel and fertiliser supplies just as farmers are planting crops, U.N. development chief Alexander De Croo said on Thursday.

Fertiliser shortages - worsened by the blocking of cargo vessels through the Strait of Hormuz - have already lowered agricultural productivity, the Administrator of the United Nations Development Programme (UNDP) told Reuters.

Lebanon's leaders accused Israel on Thursday of committing a war crime, after an airstrike killed a Lebanese journalist in the country's south, with the Israeli army saying it was reviewing the incident.

Rescuers and the reporter's employer on Wednesday confirmed the death of Amal Khalil, a 42-year-old journalist who worked for the Lebanese daily Al-Akhbar.

The civil defence agency said she was killed in a strike on a house in the village of Al-Tiri.