Switzerland's president has hit back at a regional official's call for less generous treatment of Eritrean asylum-seekers, saying that the European country can't send them home.

An official in Lucerne canton (state), Guido Graf, wrote to President Simonetta Sommaruga this week that three-quarters of applications in his region came from Eritreans, and questioned whether there are really grounds to grant everybody refugee status, allowing relatives to join them.

He said that "the mass exodus from the country is being encouraged by overly generous asylum practice."

Sommaruga retorted Thursday that half of Eritreans already are refused full refugee status. She pointed to reports of widespread human rights violations and added: "today, it is inconceivable for Switzerland or any other European country to send people back to a despotic state."