SANTIAGO, Chile (AP) — A migration crisis at the border between Chile and Peru intensified Thursday as hundreds of people remained stranded, unable to cross into Peru in an effort to return to their home country of Venezuela.

The mostly Venezuelan migrants are seeking to cross into Peru to continue on to their home country but Peru isn’t allowing them to enter because they lack documents.

While stalled at the border of the two South American countries, the migrants face the inhospitable climate that characterises the Atacama Desert, one of the driest on the planet, with extremely hot days and intensely cold nights. Some have improvised tents with blankets but they lack water and other basic services.

A group of migrants ran through the desert toward Peru, but they were turned back by Peruvian officers. Some women complained and demanded that the government of President Gabriel Boric provide a bus for them to travel to Venezuela.

Images showed migrants shoving Peruvian border patrol officers in an effort to enter the country.

Officials in Arica, the northern Chilean city that borders Peru and is around 2,000 kilometres (1,245 miles) from the capital of Santiago, declared a migration emergency Thursday.

A day earlier, the Peruvian president, Dina Boluarte, declared a state of emergency in Tacna, a town near the border with Chile, in order to “preserve domestic order” and contain the arrival of migrants. In announcing the measure, the president attributed “criminal acts” to migrants.

Boluarte said she would push for a constitutional reform to “authorise the intervention of the armed forces in the border area.” Boric, for his part, already deployed troops to the border in late February to help stop the entry of migrants.

Amnesty International urged Peru and Chile to end what it called “the militarisation” of the border. Leaders on both sides are “needlessly aggravating the situation, turning it into a humanitarian crisis that increases the risk to the lives and safety of these people,” said Erika Guevara Rosas, director of Amnesty International for the Americas.

The Chilean government summoned Peruvian Ambassador Jaime Pomareda to express its displeasure over statements by Tacna Mayor Pascual Guisa, who called Chile’s president “irresponsible” for what the envoy called an effort to transfer the country’s migration woes to the border. Pomareda did not publicly comment on the meeting.

Arica’s mayor, Gerardo Espíndola, vowed to “provide resources” to support those in need, particularly children and the elderly.

“We will act as quickly as this critical situation affecting the people stranded at the border requires,” Espíndola said.

Amid the impasse, the head of Chile’s lower house of Congress, Vlado Mirosevic, called for a humanitarian corridor involving all the countries in the region to resolve the crisis and allow migrants safe passage back to Venezuela.

Chile’s foreign minister, Alberto van Klaveren, warned there was “a significant humanitarian problem in the area” and said Boluarte’s decision “increases pressure” at the border.

The departure of migrants from Chile comes shortly after the National Prosecutor’s Office on April 10 called on prosecutors to request preventive detention for anyone caught committing a crime who could not prove their identity.

In addition, a measure is set to be debated in the lower house of Congress that would classify irregular immigration as a crime and proposes jail sentences of as many as 541 days for anyone caught entering Chile through unofficial channels.