Protesters threw Molotov cocktails and clashed with riot police outside Mexico City's National Palace over President Enrique Peña Nieto's handling of the apparent massacre of 43 trainee school teachers.

Hundreds of police in riot gear blocked access to the palace in the capital's Zocalo square, as thousands of protesters gathered in support of the students, apparently murdered after their abduction by corrupt police on September 26.

Protesters set fire to an effigy of Peña Nieto and called for his resignation.

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A petrol bomb explodes near police outside Mexico's National PalaceAFP
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Demonstrators watch as an effigy of President Enrique Pena Nieto burns outside Mexico City's National PalaceReuters
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A protester holds a knife bearing the message: "Alive they took them" in Mexico CityAFP
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A demonstrator prepares to throw a brick at riot police in Mexico CityAFP
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Protesters clash with riot police outside the National Palace in Mexico CityAFP
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Protesters join parents of the 43 missing students in a rally in Mexico CityAFP

Relatives of the missing students stood on a platform in front of the National Palace holding posters of their loved ones' faces. Amid chants for Peña Nieto to step down, family members repeated that they do not believe the government's account that the youths were killed by a drug gang,

After most of the protesters left the square, a small group of masked youths began battling police with rocks and sticks.

Police charged across the square to drive the protesters out. At least two news photographers were injured by police, who took two cameras and some lenses from an AP photographer.

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Relatives of the 43 missing students demonstrate outside the National Palace in Mexico CityGetty
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Protesters demand the resignation of Mexican President Enrique Pena Nieto during a rally outside the National Palace in Mexico CityAFP
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A demonstrator dressed as a revolutionary takes part a protest in support of 43 missing students outside Mexico City's National PalaceReuters
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Demonstrators plead with riot police during a protest outside Mexico City's National PalaceReuters
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Protesters and riot police clash in Mexico City over the presumed massacre of 43 studentsAFP

Earlier in the day, about 200 protesters clashed with police outside Mexico City's international airport.

Masked demonstrators hurled rocks, fireworks and petrol bombs at the police.

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Masked demonstrators throw petrol bombs towards riot police near the Benito Juarez International airport in Mexico CityReuters
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Demonstrators use improvised rocket launchers to shoot fireworks towards riot police near the Benito Juarez International airport in Mexico CityReuters
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Students furious at the presumed massacre of the 43 clash with riot police outside Mexico City's international airportAFP
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Riot police take cover from a flaming missile near Mexico City's international airportAFP
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Masked demonstrators block an access road to the Benito Juarez International airport in Mexico City during a protest over the 43 missing Ayotzinapa studentsReuters
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A woman lies on the ground as police scuffle with demonstrators near Mexico City's airportReuters

The 43 students, who attended a radical rural teachers college known as Ayotzinapa, disappeared after they went to the Guerrero city of Iguala to hijack buses.

Iguala police intercepted them on the mayor's orders and turned them over to the criminal group Guerreros Unidos, a gang with ties to the mayor, prosecutors have said. Prosecutors say there is evidence the gang members killed the students and incinerated their remains.

It is that link between a local government and drug gang that disgusts many Mexicans.

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Demonstrators prepare to stencil "Fuera Pena" ("out of here Pena", referring to Mexico's President Enrique Pena Nieto) on wall in Chilpancingo, in the southern Mexican state of GuerreroReuters
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Demonstrators walk past hand imprints during a protest over the 43 missing Ayotzinapa students in Ciudad JuarezReuters

Mexico officially lists 22,322 people as having gone missing in the country's drug war since 2006. The search for the missing students has turned up other, unrelated mass graves.