Nearly a month into the Middle East war, Lebanon is facing a deepening humanitarian crisis that now risks teetering over into a catastrophe, the United Nations refugee agency warned Friday.

Since March 2, more than a million people -- one in five residents -- have been forced to flee their homes, said the UNHCR.

With the numbers continuing to rise, "it is really a deepening humanitarian crisis that we here on the ground are seeing in Lebanon", said Karolina Lindholm Billing, the agency's representative in the country.

By Olivia Le Poidevin

GENEVA, March 27 (Reuters) - Large differences remain between most countries and the U.S. and India as trade ministers meet to discuss reforms at the World Trade Organization, two diplomats told Reuters on Friday.

The ministers are meeting for four days in Yaounde, Cameroon, as the organisation faces a critical test to its future amid a year of tariff-fuelled trade turmoil and large-scale disruption to shipping, energy prices and supply chains due to the Middle East conflict.

By Emma Farge

GENEVA, March 27 (Reuters) - Emergency cholera medical supplies for several African countries have become stuck in a logistical quagmire caused by the Iran war, aid officials told Reuters, raising concerns about preparations ahead of the high-risk rainy season.

The stocks stranded in Dubai warehouses are contingency supplies placed in cholera-prone countries including Chad and Sudan ahead of the rainy months starting from May to curb any future outbreak of the fast-spreading, potentially fatal diarrhoeal disease.

Here are the latest developments in the Middle East war:

- Israel reports Yemen missile fire -

Israel's military reported on Saturday a first missile launch from Yemen since the Middle East war began on February 28.

There were no reports of any casualties or damage in Israel. Yemen's Houthi movement warned on Friday it would join the war if US-Israeli attacks continue to hit its ally Iran or if more countries join the conflict.

- Thailand-Iran deal on Hormuz strait -

March 27 (Reuters) - More than 1,900 people have been killed and at least 20,000 injured in Iran since the start of U.S. and Israeli attacks, said Maria Martinez of the International Federation of Red Cross and Red Crescent Societies (IFRC) on Friday, citing figures provided by the Iranian Red Crescent.

Martinez said the Iranian Red Crescent continues to serve as the only nationwide humanitarian organization operating across the country amidst the escalating conflict.

(Reporting by Kirsti Knolle; editing by Matthias Williams)

US Secretary of State Marco Rubio said Friday he saw European readiness to help form a coalition against Iranian control of the strategic Strait of Hormuz after US-Israeli attacks unleashed a regional war.

Rubio joined top diplomats from the Group of Seven powers for talks as he assured them that the war launched a month ago would only continue for a matter of weeks.

The top US diplomat voiced alarm that Iran would seek to establish a permanent "tolling system" for vessels in the Strait of Hormuz, the narrow waterway through which one fifth of global oil normally transits.

By Tom Perry, Maya Gebeily, Laila Bassam and Emilie Madi

BEIRUT, March 27 (Reuters) - War between Israel and Hezbollah is pushing Lebanon's fragile state and society towards breaking point, straining sectarian and political faultlines as Shi'ite Muslims are displaced and enmity deepens between the Iran-backed group and its opponents.

Of all Lebanon's many crises since a 1975-90 civil war, the renewed conflict ignited by the Iran war could be its most destabilising, Lebanese analysts and figures from across the political spectrum say.

March 27 (Reuters) - The U.S. military has fired over 850 Tomahawk cruise missiles in four weeks of war with Iran, burning through the precision weapons at a rate that has alarmed some Pentagon officials and prompted internal discussions about how to make more available, the Washington Post reported on Friday, citing people familiar with the matter.

Reuters could not immediately verify the report. The U.S. Department of Defense and the White House did not immediately respond to Reuters' requests for comment.

Gulf countries and Israel came under missile fire and Israeli forces struck Iran on Saturday, as the war raged into its second month with Washington expressing hopes for progress in talks with Tehran.

In a sign that the conflict may be expanding further, Israel's military said air defences responded to a missile launched from Yemen -- the first since the start of the war on February 28, and after threats from Iran's Houthi allies to launch attacks.

March 27 (Reuters) - More than 370,000 children have been forced from their homes in Lebanon amid Israel's offensive against Hezbollah, with at least 121 children killed and 399 injured, UNICEF's representative in Lebanon, MarcoluigiCorsi, said on Friday.

(Reporting by Kirsti Knolle, editing by Thomas Seythal)