Four men appeared in a Paris court Tuesday, the first to face charges in the Paris terror attacks that left 20 people dead, including three gunmen.

French authorities also arrested five ethnic Chechens from Russia in raids in southern France, including one whom a mayor said was found with a cache of explosives. French authorities said the men had no established links to terrorism but did have ties to other crimes.

France is on high security alert after the country's worst terrorist attacks in decades. The court case and the arrests came as France's prime minister urged his nation to do some soul-searching about the country's deep ethnic divisions and declared that fighting hatred, anti-Semitism and racism was a top priority, especially in France's impoverished housing projects.

The Paris prosecutor's office said the four men in court Tuesday were suspected of providing logistical support to Amedy Coulibaly, one of the terrorists killed by police, and requested they be detained longer on weapons and terrorism charges.

Coulibaly shot a policewoman to death on the outskirts of Paris and then killed four hostages inside a kosher supermarket before being shot dead 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.

Five others arrested in the investigation were released without charge, prosecutors said.

No one has been charged with direct involvement in the Jan. 7-9 Paris terror attacks. Coulibaly claimed allegiance to the Islamic State group while the two brothers who attacked the Charlie Hebdo satirical weekly said they were backed by al-Qaida in Yemen.

In southern France, Beziers Prosecutor Yvon Calvet told reporters that authorities have not uncovered an attack plot or other terrorism connection linked to Tuesday's arrests of the five Chechens in Beziers and on the outskirts of Montpellier.

Midi Libre, the local paper, said an explosives cache was found in Beziers near a stadium and Beziers mayor Robert Menard said the man arrested had been a resident "for some time."

Calvet said the arrests Tuesday were "outside of all radical-religion context" but did not specify the suspects' ties to other crimes. Regional judicial police director Gilles Soulie said police found "very dangerous" explosives in the raids Tuesday.

In Bulgaria, a court agreed to extradite a Frenchman who knew one of the two Kouachi brothers who massacred 12 people at Charlie Hebdo. Fritz-Joly Joachin told the Bulgarian court he was innocent and wanted to return to Paris to clear his name.

Prime Minister Manuel Valls, meanwhile, 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.