Protesters broke down a door to Mexico's presidential palace on Wednesday during a demonstration demanding justice for 43 students whose disappearance nearly a decade ago shocked the country.

A few dozen protesters using a pick-up truck smashed open an entrance to the National Palace while President Andres Manuel Lopez Obrador was holding a press conference inside, television images showed.

A handful were then seen entering the building and security personnel responded to try to repel them.

Lopez Obrador described the incident a "very clear plan of provocation."

"They would like us to respond violently. We're not going to do it. We're not repressors," he said.

"The door will be fixed and there's no problem," Lopez Obrador added shortly before concluding his news conference.

Although the wooden doors of the National Palace, built during the colonial period, had previously been targeted by other protesters, it is believed to be the first time in recent years that they have managed to break one down.

Relatives of the missing students and supporters have carried out various protests in Mexico City, including a sit-in outside the National Palace demanding to meet with Lopez Obrador.

The 2014 case of the students from a teacher training college in the violent southern state of Guerrero is considered to be one of the country's worst human rights atrocities.

They had commandeered buses to travel to a demonstration in Mexico City, then went missing.

Investigators believe they were kidnapped by a drug cartel in collusion with corrupt police, although exactly what happened to them is unclear.

In 2022, a truth commission set up by the government branded the case a "state crime" and said that the military shared responsibility, either directly or through negligence.

One theory that it put forward was that cartel members targeted the students because they had unknowingly taken a bus with drugs hidden inside.

Last year, the commission found that the army was aware of what was happening and had real-time information about the kidnapping and disappearance.