A diplomatic dispute between Spain and Italy over the arrival of tens of thousands of migrants in Spain’s North African territory of Ceuta intensified Saturday after Madrid imposed border checks on Italian travelers in response to similar measures by Rome.

Italians arriving at Barcelona’s airport were subjected to random police checks after the measures took effect overnight, Spain’s state news agency EFE reported.

The Spanish government said the controls would remain in place for at least a month after Italian Prime Minister Giorgia Meloni rejected Madrid’s warning Friday that it would take “proportionate measures to protect the interests and dignity of its citizens” unless Rome lifted its restrictions by an Aug. 9 deadline.

Italy began enforcing air and sea border controls on Spanish citizens Aug. 1, following Meloni’s sharp criticism of the migration policies of Spanish Prime Minister Pedro Sanchez.

The diplomatic feud erupted after about 72,000 migrants from Morocco arrived suddenly in Ceuta late last month. Most have since returned to Morocco, but more than 80 migrants died, including people who drowned or were trampled in a stampede as they tried to cross a breakwater barrier, according to Spanish and Moroccan authorities.