Protesters expressing fury at the government’s handling of the disappearance of 43 student teachers in southern Mexico six weeks ago clashed with police in the resort city of Acapulco on Monday.

The chaotic battle, that the authorities said left 16 officers injured, broke out when riot police blocked the path of a march heading towards the city’s airport, Milenio TV reported. There was no word on the number of injured protesters, some of whom were masked and wielding machetes and large sticks.

The clashes in Acapulco took place amid an escalating political crisis sparked by the disappearance of the students in the southern city of Iguala on 26 September, after they were arrested by municipal police allegedly in league with a local drug-trafficking gang. Six people were also killed in the events of that night that began when police opened fire on three bus loads of students.

Acapulco is in the same state as Iguala, as is the famously radical teacher-training college, known as the Normal de Ayotzinapa, where the missing students are enrolled.

A wounded riot police officer is rescued from violent demonstrators during clashes near Acapulco’s airport. Photograph: Pedro Pardo/AFP/Getty Images

Calm reportedly returned to Acapulco after police permitted a group of demonstrators, headed by parents of the disappeared students, to continue to the airport that they then shut down for three hours.

As the blockade was lifted, one of the parents told reporters to expect more protests in coming days.

“We are now going back to the school to see what we organize next,” said Felipe de la Cruz who, like many of the parents, is currently camped out in the Ayotzinapa college. “We are not going to sit back and do nothing.”

The disappearance of the students had already sparked numerous peaceful demonstrations punctuated by the occasional outbreak of violence.

Tension has intensified, however, since Friday’s announcement by attorney general Jesús Murillo that a large group of young people were massacred in a rubbish tip near Iguala a few hours after the students were arrested. He said that the victims were then burned on a huge pyre for 14 hours, making identification of the remains recovered by the authorities very difficult.

The parents have accused the government of trying to close down the case.

Demonstrators hold a riot police officer during clashes following a protest in Acapulco. Photograph: Pedro Pardo/AFP/Getty Images

Prior to the announcement of the massacre, the authorities had said they recovered at least 38 bodies from nine mass graves near Iguala. On Friday, attorney general Murillo said four of these have now been identified as people who disappeared at checkpoints set up by Guerreros Unidos gang members and the municipal police.

On Saturday, a large peaceful demonstration in Mexico City ended with masked demonstrators setting fire to the wooden door of the ceremonial presidential palace in the centre of the capital.

Social media has since been buzzing with accusations that the incident was incited by provocateurs seeking to scare the general public away from the protest movement.

They pointed out that the authorities did nothing to contain the attack until the door was burning, and tweeted photographs they said showed provocateurs behind police lines when they finally appeared to disperse the crowd.

President Enrique Peña Nieto condemned that burning of the door while making a stop in Alaska en route to the Apec summit in China. “You cannot demand justice acting with violence,” he said.

Riot police stamp out flames after a fire bomb was thrown at them during violent protests in Acapulco. Photograph: Pedro Pardo/AFP/Getty Images

The crisis over the students has exposed the depth of the security crisis in parts of Mexico where criminal groups have taken control of some municipal governments, while the federal authorities appear to turn a blind eye.

It has also exploded the president’s carefully constructed international image as a reformist statesman who has left behind the drug wars associated with a counterproductive offensive against organised crime launched by his predecessor, Felipe Calderón.

The violence in Acapulco came the day before energy ministers from 15 countries are due to meet in the city for a two-day conference in the context of the government’s ambitious energy-liberalisation plans that were the jewel in the crown of the president’s reform agenda.

Peña Nieto’s trip to China also comes as questions grow over revelations this weekend that a mansion designed for the presidential family and reportedly worth $7m is owned by a company that participated in the Chinese-led consortium that won the bid to build Mexico’s first high-speed railway. The contract was annulled in a surprise announcement on Thursday, two days before the president headed for the summit in Beijing.