Thousands of Mexicans are camping out on international roads and bridges leading into the United States, in a new surge of migrants attempting to cross the border and desperately seeking asylum.

The rise in the number of migrants comes after Mexico in August once again became the single largest source of undocumented migration into the US, surpassing Guatemala and Honduras, according to US officials who provided the update anonymously because they were not authorized to release it.

The total number of Mexican adults crossing the border spiked by 25 per cent from late July to late September, while migration from Guatemala, Honduras and El Salvador declined.

Many of the Mexican migrants say they are fleeing corruption and drug-related violence - including that sparked by the recent botched arrest of one of the sons of drug lord Joaquín 'El Chapo' Guzmán.

Thousands of Mexican families have camped out on roads and bridges at the border (pictured above) to enter the United States

The migrants waiting to cross the border are camped out in tents, and in some cases, are exposed to the elements (pictured above) while awaiting to speak with border officials

The rise in the number of migrants comes after Mexico in August once again became the single largest source of undocumented migration into the US, surpassing Guatemala and Honduras, according to US officials who provided the update anonymously

That has sent Mexican families in droves to the border, where they have joined other migrants awaiting to apply for asylum relief and cross into the US, reports the Washington Post.

Images from the border show migrants camped out in tents or in some cases exposed to the elements until they can meet with border officials to request asylum.

US officials worry that a new border crisis is unfolding, reports the Post.

Among the officials' concerns was the percentage of Mexican migrants declaring that they were fleeing persecution and/or possible harm, which stops their immediate deportation and allows them to stay in the US while awaiting a hearing in US immigration court.

US officials are concerned by the number of Mexicans who declared a fear of persecution or harm, which typically stops immediate deportation. Many are fleeing corruption and drug-related violence, including the botched arrest of former drug lord Joaquín 'El Chapo' Guzmán

The Department of Homeland Security, the officials say, is especially concerned since the immigration courts already are struggling to hear a backlog of million migrants requesting relief from removal proceedings.

Neither Mexico or the US government has acknowledged the surge at the border, or the possible trouble that may be looming over an agreement between President Donald Trump and Mexico President Andrés Manuel López Obrador that previously cut down on the number of illegal crossings.

Data shows the total number of Mexican adults crossing the border spiked by 25 per cent from late July to late September. Migration from Guatemala, Honduras and El Salvador, at the same time, declined, reports the Post.

Officials say that the of Mexican families who were detained at the border also has surged.

Many of those fleeing blamed violence related to last week's botched arrest of Guzman's son, Ovidio Guzman Lopez, 28, (pictured)

The bloody, war-like confrontation in Culiacán that resulted when authorities attempted to arrest the former El Chapo's son, Ogivido Guzman Lopez, ended with his release after the drug lord's cartel struck back at the Mexican army, leaving at least 8 dead

Many of those fleeing blamed violence related to last week's botched arrest of Guzman's son, Ovidio Guzman Lopez, 28.

The bloody, war-like confrontation in Culiacán ended with his release after the drug lord's cartel struck back at the Mexican army, leaving at least 8 dead.

However, there also was a bizarre rumor that the US was welcoming Asylum seekers, reports the Post.

But there also are indications some are heading to the border with their children after hearing that the United States was opening its doors to Mexican asylum seekers.

Local officials in the Cuidad Hidalgo said hundreds of local residents in the town of 55,000 have suddenly left on a rumor that the US had recently opened a new opportunity for them to come to the border and request asylum.

There's even a weekly bus that takes residents directly to Tijuana and other border towns, offering asylum seekers a 'door-to-door package,' said Eduardo Cortés, the city manager, reports the Post.

'It's a phenomenon that took us all by surprise here,' Cortés said. 'It's like the rumor hit the streets and now people think there's a chance for them to improve their lives by moving to the United States.'