Mexican authorities have mounted a rescue operation for eight American hikers believed to have run into trouble while climbing the country's highest peak, officials said Sunday.

After a navy helicopter searched on Saturday, the rescue effort expanded into a ground operation on Sunday.

"We are working on the rescue of eight US hikers who are supposed to have had an accident in Citlaltepetl," the Puebla civil protection agency said on Twitter.

It said members of the military, the Puebla medical services, and a Mexican mountain rescue group were involved in the operation.

There were no immediate details on whether the hikers had been located, the nature of the accident, or their identities.

Citlaltepetl is an inactive volcano on the border of Puebla and Veracruz states, whose peak rises 18,372 feet (5,600 meters), making it the tallest in Mexico.

Also known as the Peak of Orizaba, the mountain is popular with climbers but has also proved deadly in the past.

On Thursday, the body of a US hiker was recovered from the peak during a risky operation in which a rescuer fell into a ravine and was injured.

In 2015, the mummified remains of two climbers were found at an altitude of 17,000 feet but could not be recovered because of the perilous terrain.

source: AFP