Lima: Peru has declared a 60-day health emergency in two provinces on its northern border, citing "imminent danger" to health and sanitation, as a regional crisis sparked by thousands of Venezuelans fleeing economic collapse escalated on Tuesday.

A Venezuelan migrant holds her passport while wait in line to take a bus to continue their travel in Tumbes, Peru. Credit:AP

The decree, published in the government's official gazette, did not give more details on the risks, but health authorities have previously expressed concerns about the spread of diseases such as measles and malaria from migrants.

Meanwhile, Brazil was sending armed forces to keep order near the Venezuelan border area, in the state of Roraima.

The exodus of Venezuelans to other South American countries is building toward a "crisis moment" comparable to events involving refugees in the Mediterranean, the United Nations said this week.