Israeli Interior Minister Eli Yishai demanded on Thursday that all illegal African immigrants be put "behind bars" before kicking them all out.

"We must put all these infiltrators behind bars in detention and holding centres, then send them home because they come and take work from Israelis," he told army radio.

Unless the government took urgent action, there would "soon be half a million to a million, and we cannot lose our country to this," said the minister, who has frequently called for the expulsion of non-Jewish immigrants, sparking cries of racism.

Violent race riots that shook southern Tel Aviv overnight sparked shock in Israel on Thursday, but also prompted top-level calls for the immediate arrest and expulsion of tens of thousands of African migrants.

The latest unrest to sweep the impoverished neighbourhoods around Tel Aviv's central bus station erupted on Wednesday night when a demonstration of around 1,000 people who were protesting against the rising number of Africans moving into the area turned violent.

"Shock, violence and hatred of foreigners in Tel Aviv" was the headline in the Maariv daily, which described scenes of chaos as demonstrators went on the rampage with sticks and stones, attacking African-run shops and smashing up a car driven by two African men.

"Blacks out!" shouted demonstrators in the crowd, while others yelled "Send the Sudanese back to Sudan," several media reports said, as other protesters derided the "bleeding-heart leftists" working to help them.

Most reports said the rally turned nasty after the crowd was whipped up by several racist speeches by right-wing MPs, several of them from the ruling Likud party of Prime Minister Benjamin Netanyahu.

"The infiltrators are a cancer in our body," Likud MP Miri Regev told the crowd, as fellow MP Danny Danon shouted: "The infiltrators must be expelled from Israel! Expulsion now!"

Police spokesman Micky Rosenfeld said 20 people had been arrested on suspicion of vandalising shops and attacking cars driven by Africans, but added that there were no reports of anyone being injured.

The police have also extended the remand of seven Israeli minors accused of attacking African immigrants earlier this week, he said.

Interior ministry statistics show there are more than 60,000 African immigrants living illegally in Israel.

Some are asylum seekers fleeing persecution, while others are economic migrants. Almost all of them sneak across the border from the Egyptian Sinai and end up living in the run-down neighbourhoods around Tel Aviv's bus station.

The issue of illegal immigration from Africa has thrown into relief sharp divisions within Israel, with many top officials, including Netanyahu, warning that their growing numbers pose a major threat to the security and identity of Israel.

Wednesday's nights violence made headlines in all the main Hebrew-language newspapers, as well as on the TV and radio stations, with army radio denouncing it as a "pogrom."

In a bid to halt the influx of immigrants from Africa, Israel has been building a 250-kilometre (155-mile) fence along the Egyptian border. It has also built a vast detention centre near the border to house anyone caught crossing the frontier.

At the start of the year, Netanyahu said he was planning to visit several African capitals to discuss the issue of immigration, but so far no such plans have been made public.