Wading through knee-deep mud, some limping, hundreds of Venezuelan migrants battle against fatigue with their eye on the prize: hope for a new life in the United States.

With sore feet, injuries and dented spirits several days into their ordeal - still far from halfway - they trudge in single file through the infamous Darien Jungle linking Colombia to Panama.

With a long way still ahead through Central America and Mexico, the group of men, women and children, some babies, already has many horrors to recount.

And it may all have been in vain.

Last week, the United States announced that Venezuelans arriving by land without travel documents will be returned to Mexico.

For Jesus Arias, 45, sometimes one has to "risk one's life to have a future."

"But honestly, I would not advise anyone to come through the jungle. It is very hard," he told AFP as he and others arrived at an Indigenous settlement in Panama, Canaan Membrillo - one of several border control points in the 575,000-hectare (1,420,900-acre) jungle.

Arias arrived at Canaan Membrillo in a T-shirt and shorts, carried by other men in the group after injuring his knee.

'We're going anyway'

He undertook the journey knowing it would be tough because "there is no future in Venezuela. Every day it gets worse."

He may have no choice but to go back to the crisis-hit country, which is wracked by violence, insecurity and a lack of essential services. The UN Refugee Agency says 6.8 million refugees and migrants have left Venezuela since 2014.

Under the US decree, only 24,000 Venezuelans who apply under a humanitarian program will be granted entry.

"We're going anyway," said Arias. "Even if we are stopped, at some point we will enter."

The number of Venezuelans making the Darien crossing reached a record high in 2022 - some 133,000 between January and mid-October, according to authorities in Panama.

For the whole of last year, the figure was 2,800.

Venezuelan Nelida Pantoja, 46, saw "many dead, many mountains, many rivers that carried off many people... It was horrible," she told AFP at Canaan Membrillo.

But like most of her fellow migrants, she vowed to "keep trying" until she gets into the United States.

Darwin Vidal, 33, said he was struggling to garner the strength for what lay ahead: battling not only rough terrain but also being at the mercy of poisonous snakes and other wild animals, as well as criminal groups.

"I got lost for three days in the jungle with my family. With my children, we were going too slowly. We couldn't keep up with the group, we fell behind, and got lost" for a scary while, he said.

Rusbelis Serrano, 18, said she thought the worst was over.

"My mom, my dad, my brothers are waiting for me" in the United States, Serrano told AFP.

"I don't have much left. I have to keep trying."

The authorities in Panama say at least 100 people have died crossing the Darien since 2018, about half of them in 2021 - the deadliest year so far.