There are more than 350 indigenous languages in Mexico

The two elderly men in the village of Ayapan, Tabasco, have drifted apart, said Fernando Nava, head of the Mexican Institute for Indigenous Languages.

He used the example to draw attention to the threat to indigenous languages across Mexico.

More than 20 of these are under threat of extinction.

'Little in common'

Dr Nava played down reports of an argument between the two Ayapan residents, both in their 70s.

"We know they are not to say enemies, but we know they are apart. We know they are two people with little in common," he told the BBC News website.

"They are really personal reasons that they don't speak to each other. We don't have to think of a war."

The men are the only fluent speakers of their local version of the "Zoque" language.

Other languages from the same root are spoken in the Mexican states of Veracruz, Oaxaca and Chiapas.

The Zoque tribe is thought to descend from the Olmecas and its members are spread around the south of Mexico.

The indigenous languages institute is trying to encourage more local people to speak Ayapan Zoque, and hopes the two men will pass the language on to their families.

It is also being recorded.

"We hope in a few years to be talking about new speakers of the language," Dr Nava said.

Mexico is one of the countries in the world with the richest diversity of languages.

More than 350 indigenous languages are spoken within its territory.

According to the UN, one language disappears across the world every two weeks.