By David Brunnstrom and Olivia Le Poidevin

April 22 (Reuters) - Former Costa Rican vice president Rebeca Grynspan, a candidate to head the United Nations, vowed on Wednesday that peacemaking would be her first priority if chosen, while warning that trust is waning in the world body and time running out to restore it.

"Peacemaking is the purpose of this organization," Grynspan, one of four candidates vying to become the next U.N. secretary-general from next year, told a hearing on her candidacy at the U.N. in New York.

The United States has vowed to blockade Iran's ships until the country makes a deal to end their war. But is the blockade working?

Analysts and ship-tracking data paint a complicated picture. Shifting objectives and shadowy activity by vessels making the success of the US operation hard to measure.

"There's been confusion over the scope and the parameters of the blockade because of conflicting information given by the US administration and some delays in when information has been released," Bridget Diakun, an analyst at shipping journal Lloyd's List Intelligence, told AFP.

US Treasury Secretary Scott Bessent on Wednesday defended the Trump administration's recent about-face to temporarily extend a sanctions waiver that allowed the sale of Russian oil already at sea.

The month-long relief announced last Friday was meant to cool soaring energy prices. But it came just two days after Bessent told reporters that Washington would not renew the waiver.

The latest move allowed for purchases of oil and petroleum products that had been loaded onto vessels as of Friday, through 12:01 am (0401 GMT) on May 16.

The latest developments in the Middle East war:

- US Central Command turns back 31 vessels -

US Central Command (CENTCOM) said late Wednesday that it had also "directed 31 vessels to turn around or return to port" as part of its own "blockade against Iran".

It said on X "the majority of vessels have complied with US directions" adding that "most vessels turned around have been oil tankers".

- Oil jumps before easing -

Lebanese town official Sharif Badreddine begged his youngest son not to leave to fight for Hezbollah against Israel in the country's south, but as the tearful father buried his child he could not hide a sense of pride.

In the face of a government push to disarm the movement, its supporters call on a long-held enmity with Israel, deep religious beliefs and backing from Iran to justify their sons' sacrifice in the group's latest war that has killed thousands in Lebanon.

"Before he left, I told him, 'Don't go, the situation is bad,'" Badreddine, 67, told AFP.

Israeli attacks on Lebanon during its latest war with Hezbollah damaged or destroyed more than 50,000 housing units in the country, a government estimate found on Wednesday.

"Within about 45 days (of the war), we had 17,756 destroyed housing units and 32,668 damaged housing units," Chadi Abdallah, head of the National Council for Scientific Research (CNRS), told AFP.

Israeli attacks on Lebanon killed more than 2,400 people and displaced more than a million since Iran-backed Hezbollah drew the country into the Middle East war on March 2.

By Ahmed Rasheed, Maha El Dahan and Timour Azhari

BAGHDAD/DUBAI April 21 (Reuters) - The United States has halted a shipment of about $500 million in cash bound for Iraq and suspended parts of its security cooperation with Baghdad, in a move aimed at pressuring the Iraqi government over the actions of Iran-backed militias, Iraqi sources told Reuters.

By Nidal al-Mughrabi, Ali Sawafta and Haseeb Elwazeer

GAZA, April 22 (Reuters) - Palestinians in one of the only Gaza cities not overrun by Israeli ground forces during the war will vote this weekend in municipal elections that will feature some pro-Hamas candidates, offering a rare barometer of the militant group's popularity.

The vote in Deir al-Balah is part of Palestinian Authority municipal elections that Palestinians have cast as a display of national unity against a U.S. plan for Gaza that they believe intends to entrench their separation from the occupied West Bank.

By Jessica Donati

DAKAR, April 22 (Reuters) - The Trump administration is in talks with the Democratic Republic of Congo to resettle 1,100 Afghans who have been stranded in Qatar awaiting U.S. visas, according to an advocacy organisation that works on their behalf.

The discussions underscore the legal hurdles facing Afghans who fled the Taliban after U.S. immigrant visa processing for Afghan nationals was effectively halted, leaving them in limbo more than four years after the U.S. withdrawal from Kabul.

By Maya Gebeily and Pesha Magid

BEIRUT/JERUSALEM, April 22 (Reuters) - Lebanese and Israeli envoys will meet for the second time in two weeks in Washington on Thursday, building on nascent contacts between the states, with Lebanon hoping for the extension of a shaky ceasefire between Hezbollah and Israel.

The 10-day, U.S.-mediated ceasefire is set to expire on Sunday. Underlining its fragility, Iran-backed Hezbollah said on Tuesday it had fired rockets at northern Israel in response to Israeli violations, while Israel also accused the group of breaches.