Thousands of migrants are marching through southern Mexico as part of a mass protest to demand the end of detention centres.

Last month, 40 people were killed when fire ripped through a facility in Ciudad Juárez, a city on the US border.

They are hoping to reach the capital Mexico City in about 10 days.

The caravan of about 3,000 people started walking at dawn on Sunday from the Mexican city of Tapachula, near the Guatemalan border. On Sunday they slowly made their way through the rural state of Chiapas, walking in more than 35C (95F) heat.

They are mainly from Central America, Cuba, Venezuela, Ecuador and Colombia.

Demanding better treatment for migrants, some are carrying signs reading "Government Crime" and "The Government Killed Them", referring to those who died in the fire.

It is unclear how many of the protesters may continue on to the US border, as has happened in the past. Large groups have often been broken up by authorities well before they reach either Mexico City or the US-Mexico border.

Mexico is struggling to deal with an influx of migrants who are fleeing instability, violence and poverty in their own countries.

While most are hoping to reach the US, some do apply for asylum in Mexico.

The immigration centre in Tapachula - the biggest in Mexico - is one of the main bottlenecks on their journeys. Nicknamed the "migrant prison", refugee processing offices in the city are overwhelmed.