The U.S.-Mexico border is the world's deadliest land migration route, according to U.N. migration agency figures published, with hundreds losing their lives attempting to make perilous desert crossings.

The International Organization for Migration (IOM) documented 686 deaths and disappearances among migrants on the frontier last year, but the actual figure is likely higher due missing data, including from the Texas border county coroner's offices and the Mexican search and rescue agency.

In a landscape of sweeping desert, canyons and cactus-studded hills, migrants fall prey to heat stroke in summer and hypothermia in winter, U.S. border officials have said. Some bodies are never found.

Paul Dillon, spokesperson for IOM, said that the figures recorded "represent the lowest estimates available."

"The alarming figures are a stark reminder of the need for decisive action to create regular legal migration pathways," he told reporters in Geneva.

IOM said that nearly half of the deaths recorded last year were linked to the crossing of the Sonoran and Chihuahuan Deserts.

The number of deaths and disappearances documented by IOM along the border represents nearly half of the 1,457 cases recorded throughout the Americas last year.

"One of the most concerning trends that IOM has seen in the Americas was the increase in deaths on migration routes in the Caribbean," Dillon said.

He said that 350 deaths had been documented in 2022, compared with 245 in 2021 and less than 170 recorded in prior years. Most of the victims on Caribbean migration routes were people from the Dominican Republic, Haiti and Cuba.

The Darien Gap, a jungle border crossing between Panama and Colombia, saw 141 documented migrant deaths last year, according to IOM.

"The remote and dangerous nature of this area and the presence of criminal gangs along the route means that this figure likely does not represent the actual number of lives lost," Dillon said.

Panama announced new measures last week to curb rising migrant crossings through the Darien Gap, which reached an all time high this year.