Officials say more people may be found as search continues following abduction on way to US border.

The people, who were travelling across the country to the United States border as migrants, said they had been abducted on Tuesday when their bus stopped at a petrol station about three hours from the northern city of Monterrey.

They had been found in several groups in the central state of San Luis Potosi and the neighbouring state of Nuevo Leon to the north, Defence Minister Luis Cresencio Sandoval announced on Thursday.

At least 33 had been found on the day of the initial abduction, with more people recovered early Thursday morning. The bus was estimated to carry about 50 people, and two drivers from the trip remain missing.

“We’re going to keep looking, and the drivers are a priority,” Sandoval said at a government news conference, adding it was possible that more migrants may be found, because there was not a clear accounting of how many were on the bus to start with.

Sandoval said that 650 police and army troops were involved in the search. He did not identify the cartel responsible for the kidnapping but acknowledged the Gulf cartel and other gangs operate in the area.

No arrests have been made.

An unnamed person from Honduras, speaking in a video released by San Luis Potosi state prosecutors, said the bus had departed from the southern state of Chiapas.

A person who stopped the bus demanded a payment of 40,000 Mexcian pesos ($2,250) from the bus owner and kidnapped the migrants, the Honduran national said.

It was the latest mass kidnapping in Mexico, where migrants bound for the US must pass through areas rife with drug violence that lack adequate law enforcement, making travellers vulnerable to organised crime.

Several busloads of Nicaraguans were kidnapped in December of last year in the northern state of Durango in one of the biggest known kidnappings of migrants in Mexico in recent years.

In early May, a government report said more than 2,000 migrants were kidnapped by smuggling gangs and drug cartels in 2022. Mexico’s national immigration agency said authorities had freed 2,115 migrants of all nationalities kidnapped by gangs that year.

Disappearances have become a widespread problem in Mexico. A study by Quinto Elemento Lab found that an average of 32 people disappeared a day across the country in 2022.