Panama says it’s halving the maximum time for tourism visits by people from Colombia, Venezuela and Nicaragua to 90 days.

President Juan Carlos Varela’s announcement of the plan Friday comes amid concerns that many visitors have been staying on in Panama after coming as tourists. Panama will also seek to verify that people seeking to enter as tourists have sufficient funds.

While there has long been immigration from neighboring Colombia, many people are now arriving from crisis-wracked Venezuela. Many of the migrants stay and work under the table. Some have been linked to crimes, angering some Panamanians.

There are no figures on illegal immigration, but about a quarter million people from the three countries gained residency in Panama since 2010.