ON MAY 28th it was the turn of Yorusalem Mestun, a 22-year-old Eritrean asylum-seeker in hot-pants. Five young Israelis smashed the glass door of her internet café and pulled a knife on her, while her Jewish neighbours looked on. The police came, checked her visa and left without, she said, offering help or sympathy.

Attacks on Israel's fast-growing population of African asylum-seekers, mainly from South Sudan and Eritrea, are rising. Hundreds of Jews led by settlers from the West Bank, where Palestinians hope to create their state, recently marched through districts of south Tel Aviv, Israel's commercial capital, where black immigrants proliferate, chanting “Africans Out!” Pumped up with angry excitement, the middle-aged chef of a fast-food shop, in HaTikva, a working-class district where migrants are also settling in large numbers, offers passers-by “grilled kushi”, provocatively meaning “grilled blacks”, and suggests getting rid of the immigrants by throwing grenades at their tenements. In recent weeks, several homes and a kindergarten for Africans have been firebombed.

Liberal Israelis have staged anti-racist rallies. A generation after their arrival, over 120,000 Ethiopian Jews have been integrated. The country has received an estimated 60,000 black asylum-seekers. It is not the first to struggle when large numbers of people suddenly arrive.

On May 29th the prime minister, Binyamin Netanyahu, said he was adding African “infiltrators” to his list of threats to the Jewish homeland. He said he shared the rioters' pain and promised to solve the problem by completing a wall along the border with Egypt. He said he would also build the world's largest detention centre—and deport all those within, starting with the South Sudanese.

Until 2009 the 15,000 or so asylum-seekers entering via Sinai every year were banned from coming within a radius of 30km (19 miles) of Tel Aviv. Since the government revoked that order, the security forces, after catching immigrants crossing, verify their identity and then pack them off to Tel Aviv. Scores of destitute new arrivals bed down every night in a park near the main bus station.

Israeli officials say they are loth to improve conditions in case even more are encouraged to come. The interior ministry bans the immigrants from work and refuses to process asylum applications from friendly countries such as Eritrea, though it is a dictatorship. “How can a country founded by refugees turn against them?” asks Yohannes Bayu, an Ethiopian who arrived 15 years ago and now runs the country's only shelter for asylum-seekers.