Mexico has breached an international human rights charter by bringing terror charges against two social media users who wrongly reported an armed attack on a local school, a lawyer for the accused said.

The man and the woman face the threat of as much as 30 years in prison because they posted messages online and via Twitter late last month, warning that gunmen had stormed a primary school in the eastern coastal state of Veracruz.

They took five children, an armed group, Gilberto Martinez, 48, a math teacher, wrote on his Twitter account on August 25 as fear spread that gunmen had besieged the school.

Police allege that Maria de Jesus Bravo, 57, a local radio host, authored similar posts that sowed panic as parents rushed to save children from the reported attack.

The rumors spread quickly after witnesses spotted a burning car near the school, said Fidel Ordonez, an attorney for the accused, and prompted a crackdown by authorities on social media users which resulted in the arrests.

The two face terrorism charges that could get them 30 years in jail, Ordonez said, but their defense team says the case violates two articles of the United Nations International Covenant on Civil and Political Rights, which Mexico signed.

You cannot regard us as terrorists or saboteurs, the pair said in court documents filed by their lawyers on Monday, adding that they were simply exercising their right to free speech. In the Martinez Twitter posts, the teacher says that he is just relaying information from other sources.

Article 19 of the charter states everyone shall have the right to ... seek, receive and impart information and ideas of all kinds, regardless of frontiers, either orally, in writing or in print, in the form of art, or through any other media of his choice.

The Veracruz prosecutor's office did not immediately answer a request for comment on Tuesday. Local media quoted him as saying that the pair would be prosecuted under state laws banning acts which cause alarm or terror among the population.

International pressure should help to get the pair released in the next few weeks, Ordonez told Reuters by telephone.

I have a very strong feeling that they will be released because this is truly an attack on civil rights, he added.

The pair are still being held in jail and likely to remain there until the next hearing which could come late this month or in early October, Ordonez said.

Mexico's efforts to combat drug smugglers have left more than 42,000 dead since President Felipe Calderon sent the army to confront traffickers less than five years ago.

However, the failure of Mexico's flawed justice system to convict suspects for serious crimes has sent authorities scrambling to find other ways to make charges stick.

President Felipe Calderon last week labeled as 'terrorists' suspected drug gang members accused of a deadly arson attack in the industrial northern city of Monterrey.

Veracruz, an oil-rich state on the Gulf of Mexico, has avoided the worst of the violence.

However, several attacks in recent months have had citizens turning to social media for unfiltered news, said Rupert Knox of Amnesty International. He said that the detained Mexican pair had been made to suffer for the overall lawlessness.

This is an insecure environment where people turn to social media to try and keep themselves safe, he said. These people are being scapegoated for the panic that ensued but the case should not stand up to scrutiny.