Five Russians have been arrested in southern France, including one with a cache of explosives, a local mayor said Tuesday as four other men appeared at a court in Paris, the first to face charges in the Paris terror attacks.

The reports came as the French prime minister asked his nation to do some soul-searching about the country's deep ethnic divisions and declared that fighting hatred, anti-Semitism and racism was an urgent priority, especially in France's impoverished housing projects.

Beziers Mayor Robert Menard confirmed the arrests Tuesday in Beziers and Montpellier of five men of Chechen origin and said the man arrested in Beziers had been a resident "for some time."

Midi Libre, the local paper, said an explosives cache was found in Beziers near a stadium but prosecutor Yvon Calvet told Midi Libre it wasn't immediately clear whether a terror attack was planned. Prosecutors planned a news conference later Tuesday.

France has been on high alert since three days of terror in the Paris region left 20 people dead, including the three gunmen, earlier this month.

The Paris prosecutor's office said the four men in court Tuesday were suspected of providing logistical support to Amedy Coulibaly, one of the dead terrorists.

Coulibaly shot a policewoman to death on the outskirts of Paris and then seized hostages inside a kosher supermarket, killing four before he was killed by police. It is not clear whether the four suspects, all in their 20s, were involved in plotting the attacks or even aware of Coulibaly's plans.

The Paris prosecutor's office said five others arrested in the investigation were released without charge.

No one has been charged for direct involvement in the Jan. 7-9 terror attacks. Coulibaly claimed allegiance to the Islamic State group while the two brothers who attacked the Charlie Hebdo newspaper said they were backed by Al Qaeda in Yemen.

Prime Minister Manuel Valls told journalists Tuesday that the attacks should force France to look at the "apartheid" within. The conservative Socialist whose hard line on Islamic extremism has won many fans said he wasn't making excuses for crime or terrorism, "but we also have to look at the reality of our country."

Valls said memories have dimmed of the three weeks of riots by disaffected youths in 2005 that shook France.

"And yet, the stigmas remain ... a territorial, social and ethnic apartheid that has imposed itself on our country," he said. "The social misery is compounded by the daily discriminations, because someone does not have the right name, the right color of skin, or because she is a woman."

In response to the 2005 riots, the French government spent hundreds of millions of euros (dollars) to improve conditions in its rundown suburbs, with little success. Unemployment among young people in the housing projects is well above the national average and state buildings are often targeted for vandalism and arson.

"The fight against hatred, anti-Semitism in all its forms, racism — these fights are absolutely urgent," Valls said. Young people who refused to take part in a national minute of silence for the terror attack victims "are symptoms of something that is not going well."

In Athens, an Algerian man suspected of jihadi terrorist links in Belgium appeared before a Greek prosecutor for an extradition hearing on being sent to Belgium. The suspect, whose name was not released, was detained Saturday in Athens, where he lives.

Belgium launched a large anti-terrorism sweep last week, during which two suspects were killed and one wounded, that netted several returnees from Islamic holy war in Syria.