The Mexico-United States border was the world's most dangerous land route for migrants in 2022, with nearly 700 dying or going missing, the United Nations migration agency said on Tuesday.

"The International Organization for Migration (IOM) documented 686 deaths and disappearances of migrants on the US-Mexico border in 2022, making it the deadliest land route for migrants worldwide on record," it said.

"The figure represents nearly half of the 1,457 migrant deaths and disappearances recorded throughout the Americas in 2022, the deadliest year on record since IOM's Missing Migrants Project began in 2014."

It said lack of official data --notably from coroners' offices around the Texas border with Mexico and from the Mexican search and rescue agency -- meant the true figure was likely to be far higher.

Nearly half the deaths recorded -- 307 in total -- were of people attempting to cross from Mexico to the United States via the Sonora and Chihuahua deserts, the IOM said.

That was far more than the number of deaths officially registered in other desert regions used as irregular migration routes, such as the Sahara.

The IOM said the "alarming" numbers "reflect the fatal consequences" of countries failing "to ensure safe, regular migration routes".

"Addressing the root causes of irregular migration, enhancing humanitarian assistance and providing better protection for vulnerable groups are essential steps in safeguarding the lives of migrants seeking a safer future," it said.