Israeli cave explorers said Thursday that a salt cave with striking stalactites near the Dead Sea is the world's longest, beating the previous record-holder in Iran.

The cave named Malham, stretching over 10 kilometres, runs through Mount Sodom, Israel's largest mountain, and spills out to the southwest corner of the adjacent Dead Sea.

Pale salt stalactites hang from the ceilings, and some of the walls sparkle with salt crystals. Drops of salty water are visible at the tips of some of the stalactites.

Malham became known to researchers through the work of Amos Frumkin, founder and director of the Hebrew University's Cave Research Centre, who in the 1980s mapped around five kilometres of it.

But in 2006, researchers mapped over six kilometres of the N3 cave in southern Iran's Qeshm island, granting it the widely recognised status of the world's longest salt cave.

Two years ago, Israeli spelunker Yoav Negev decided to complete Frumkin's work, reaching out to Bulgarian cave explorers for reinforcements with the promise of a warm winter adventure.

Negev, founder of the Israel Cave Explorers Club, joined forces with Boaz Langford, a researcher at the university's research centre, to organise a delegation of eight European spelunkers and another 20 locals.

They spent some 10 days mapping the cave in 2018.

A second 10-day expedition this year with 80 local and international spelunkers completed the measuring and mapping of the cave with lasers, determining its length at more than 10 kilometres.

Mount Sodom is essentially a huge salt block covered by a thin but resilient layer of cap rock.

The rare desert rains find their way through cracks in the cap rock and dissolve the salt to form small caves that flow down toward the Dead Sea.

Even in the short period of time since Frumkin's mapping, the cave's structure has changed, and will continue to do so.

Much of the cave's interior is covered by a fine dust that blows in from the desert. Massive slabs of salt, some amber-coloured from dust and minerals, jut out in dramatic formations.

A thin slab appearing to have been sliced out is nicknamed "The Guillotine," while twin slabs in a different hall earned the title of "The Ten Commandments."

Reporters touring the site clambered and crawled through the narrow passages before reaching the "wedding hall," where hundreds of white stalactites of various shapes and lengths created a festive backdrop.

To Negev, Malham was in "a category of its own." "There's nothing like it in Israel," he said, claiming that no other cave came even close to the 10-kilometre mark.

Negev pointed to its vast network of "caverns, passageways, piers, plateaus, one over another".

He called it "the most impressive and complex in Israel... And one of the most beautiful and fascinating ones I've been in".

Negev downplayed the significance of retaking the title from Iran -- Israel's main enemy -- saying he had "excellent ties" with Iranian spelunkers through social media and professional conferences.

"The political rivalry creates a desire to connect and mutual curiosity," he said. "They're really excellent spelunkers." "I wish I could visit there," he said of Iran and its caves.