A bus carrying migrants overturned in southern Mexico on Friday, leaving at least 18 passengers dead and 27 injured, authorities said — the latest fatal road crash involving US-bound migrants.

The dead, three of them minors, were from Venezuela and Haiti, according to a statement from the prosecutor's office in Oaxaca state.

The accident happened at around dawn on a highway linking Oaxaca and the neighboring state of Puebla, it said.

The injured were taken to hospital for treatment, it added.

Images released by state authorities showed the wreckage of the bus lying on its side on a highway winding through hills.

Thousands of migrants from different countries have been traveling across Mexico in buses, overcrowded trailers and atop freight trains in an attempt to reach the US-Mexican border.

They run the risk of fatal accidents, kidnapping by criminal groups and extortion by corrupt officials.

More than 8,200 migrants have died or disappeared in the Americas since 2014, most of them while trying to reach the United States via Mexico, according to the International Organization for Migration.

The US-Mexican border is the "world's deadliest migration land route," with 686 deaths and disappearances in 2022, the IOM said last month.

On Sunday, at least 10 Cuban migrants were killed and 25 injured when a cargo truck carrying them overturned in the southern state of Chiapas.

In early August, at least 18 people died and 23 were injured after a bus carrying local passengers and migrants from countries such as India, the Dominican Republic and some African nations plunged into a ravine in the state of Nayarit.

And in December 2021, 56 mostly Central American migrants were killed and dozens injured when a people smugglers' truck carrying around 160 people overturned in Chiapas.

The Mexican government has admitted to being overwhelmed by the number of migrants crossing its territory, the vast majority of whom are from Central America, Venezuela, Cuba and Haiti.

Mexican authorities said they detained more than 189,000 migrants last month, while the US border patrol has reported 1.8 million apprehensions between October 2022 and August 2023.

Senior US and Mexican officials pledged Thursday to redouble their efforts to tackle irregular migration through measures such as modernizing border security, increasing legal avenues and addressing the root causes.

The two countries were committed to expanding "safe, orderly and lawful pathways for migrants" but with "strict consequences" for those who enter the United States illegally, US Homeland Security Secretary Alejandro Mayorkas said after talks in Mexico City.