A law passed by Denmark’s Parliament on Thursday allows asylum seekers to be sent outside Europe to await the review of their applications.

In Greece, high-tech “sound cannons” are being used to deter migrants from crossing into the European Union from Turkey.

Both controversial new strategies highlight broader efforts to tighten immigration controls across some countries in Europe amid the pandemic.

Greek border police are experimenting with long-range acoustic devices that can produce sounds as loud as a jet engine, the Associated Press first reported. Mounted on an armored truck and aimed at the Turkish border, the “sound cannon” emits deafening blasts of noise and effectively creates a wall of sound that deters people from approaching.

The powerful sound waves “can cause significant pain and shock to the human body, causing exposed people suffering that go from serious health problems and severe pain to deafness,” Euro-Mediterranean Human Rights Monitor, a Geneva-based independent organization, warned Thursday.

Similar devices have been used around the world to crack down on protests or keep wildlife away from airport runways, the group noted, calling the strategy of creating a sound barrier against migrants “disturbing.”

Human rights advocates have questioned whether the use of the cannons violates international law, and the European Union has expressed concerns and said it will be seeking more information from Athens. Member nations have the freedom to decide how to police their own borders, but the methods they use “should conform to European fundamental rights, including the right to dignity,” European Commission spokesman Adalbert Jahnz told the AP.

The sound cannons are part of a larger strategy to create a high-tech barrier that will prevent migrants from entering Greece in hopes of seeking asylum. Artificial intelligence will be used to analyze potentially suspicious movement captured by long-range cameras, and the country is also experimenting with using the technology to conduct lie detector tests during interviews with asylum seekers, according to the AP.

Earlier this year, the U.N. refugee agency rebuked E.U. member states for pushback and violence against refugees at Europe’s borders.

Though the number of asylum seekers arriving in Europe has slowed amid the pandemic, many experts predict that the trend will be short-lived. Last month, thousands of migrants swam or waded from Morocco to the Spanish enclave of Ceuta, prompting Spain to declare a crisis and send in its military. One Greek police officer told the Agence France-Presse that the sound cannons were a tool designed to be deployed in the case of an “attempted mass incursion into Greek territory.”

In Denmark, attempts to discourage migration have taken on a different form: A law that passed Thursday means asylum seekers can be sent to another country outside Europe while they wait for their cases to be reviewed.

“If you apply for asylum in Denmark, you know that you will be sent back to a country outside Europe, and therefore we hope that people will stop seeking asylum in Denmark,” Rasmus Stoklund, a spokesman for the Danish government, told broadcaster DR, according to Reuters.

Although it’s not yet clear what countries will take in refugees under such an arrangement, Denmark and Rwanda recently signed a memorandum of understanding that has led to speculation that migrants will probably be relocated to Africa.

Human rights advocates say the move means refugees will end up in countries with fewer resources, potentially jeopardizing their safety and well-being, and questioned how Denmark will be able to monitor the treatment that refugees receive in other countries and ensure that their human rights are not violated. The United Nations High Commissioner for Refugees warned last month that the policy could be the start of a “race to the bottom” as other wealthy European nations seek to offload responsibility for asylum seekers.

Denmark, one of the wealthiest countries in Europe, has increasingly taken a hard-line stance on migration in recent years. The Danish Refugee Council said in a statement that sending refugees to a third country was analogous to Australia’s much-criticized policy of housing asylum seekers in offshore camps, and warned that the model has meant that migrants face “physical assault, slow asylum proceedings, lack of access to health care and lack of access to legal assistance.”