Paris (CNN) -- Ten suspected Islamists were arrested in fresh raids across France on Wednesday morning as the country widens a clampdown on suspected extremists after a deadly shooting spree last month, the Interior Ministry said.
The raids took place in the cities of Roubaix, Lyon, Valence, Pau, Marseille and Carpentras and in the Lot et Garonne region, the Interior Ministry said.
Meanwhile, 13 alleged radicals arrested Friday were placed under formal investigation for "criminal conspiracy in connection with a terrorist enterprise," and possession and transportation of weapons, officials said.
The formal warning is a point in the French legal system that comes after an arrest and before formal charges are filed.
Nine of the 13 have been jailed, including Forsane Alizza leader Mohamed Achamlane.
The other four were released Tuesday but remain "under judicial control," according to Achamlane's lawyer Philippe Missamou.
On Tuesday, a French prosecutor said the detained radical Muslims were preparing for holy war.
Forsane Alizza and Achamlane were "calling for the establishment of an Islamic caliphate in France and calling for the implementation of Sharia law and inciting Muslims in France to unite for the preparation of a civil war," Paris prosecutor Francois Molins said.
The group was reportedly linked to Mohammed Merah, who was accused of killing seven people in the south of France in March before police killed him after a 32-hour siege of his apartment in the southwestern city of Toulouse.
Presidential contender Francois Hollande declined to be drawn by French radio station RTL on Wednesday on whether he felt the arrests were linked to the upcoming elections, with the first round due later this month and a second round in May.
The Socialist candidate, seen as incumbent Nicolas Sarkozy's chief challenger, expressed some surprise, however, that the arrests were being carried out now, after the terror attack by Merah.
"I'm not questioning at all what is being done," Hollande told RTL. "I'm simply saying that we should, or could, perhaps have done more sooner."
Francois Bayrou, a centrist presidential candidate, told French news channel I-télévision he was concerned by the very public nature of the raids on suspected extremists.
"That the state has the responsibility to punish them, that is one thing," he said. "But when it's done in front of journalists, in front the cameras, I think that's surprising. These kinds of police interventions should not take place like this, it's as if they are advertising."
Senior Socialist Party lawmaker Martine Aubry raised similar concerns, speaking to French radio France Info.
"If these Islamic people are so dangerous, obviously we have to arrest them. But maybe it should have been done before. It's surprising that it's happened just after the Merah case," she said. "I agree on being firm, but not just for show. I'm always shocked to see the cameras there. Let justice do its job."
But Interior Minister Claude Gueant, speaking to CNN affiliate BFM-TV on Wednesday, denied any suggestion that the raids were linked to politics.
"I can give you an indication of the profile of these people, the whole group," he said. "They have been to Afghanistan and Pakistan, have scoured instructions, documents on the creation of explosives, have confirmed jihadist sentiments, support the actions of Mohammed Merah, who want to be martyrs themselves. And all these elements together were judged sufficient by the magistrate and led to their arrest.
"Just because there is a presidential election, any type of election, do we stop protecting French security? Of course not."
Molins, the prosecutor, said Tuesday the investigation into Forsane Alizza began in October 2011, and the arrests were not connected to Merah's rampage.
Achamlane "united around him a number of individuals who for several months had undergone physical training and received religious indoctrination in order to commit violent acts on French territory," Molins told reporters.
The radical leader was "known for his anti-Semitic stance and condemned for publicly violating French penal code," the prosecutor said.
Members of his group held "discussions during a meeting held in Lyon in September 2011 about a plan to kidnap a judge based in Lyon," he said.
But Achamlane's lawyer, Missamou, rejected the accusations against his client, saying the arrests were related to France's upcoming presidential election.
"I think the current period lends itself to these kind of arrests. They are looking for Muslims, fundamentalists, extremists, radicals in order to fit in with a political strategy, purely for electoral reasons," he told CNN.
Missamou said his client was innocent and "has never committed nor planned to commit acts of terrorism."
Achamlane regrets some of the comments he has made in the past, saying they were made to attract the attention of the media to the group's cause, Missamou said.
"Their fight is to defend the cause of French Muslims who they believe are victims of injustice, of racism from the French authorities," he said.
Another of Achamlane's lawyers, Benoit Poquet, released a statement denying any kidnapping plot.
The Interior Ministry announced Monday it had deported two Muslims and plans to expel three more.
Gueant said the moves were part of "an acceleration of the deportation procedures of foreign Islamic radicals."
An Islamic militant from Algeria who was involved in 1994 attacks in Marrakech, Morocco, was sent to his home country Monday, the statement said. In addition, a Malian imam was returned to his home country for sermons that promoted anti-Semitism and rejection of the West, it said.
Deportation proceedings also have started or are planned against three others: an imam of Saudi nationality, a militant Islamist from Tunisia and an imam from Turkey, the statement said.
It cited provisions in the law governing aliens and political asylum, saying the statutes "allow this type of decision with regards to the 'urgent need for state security or public safety' or 'conduct likely to harm the fundamental interests of the state.' "
According to the statement, other expulsions will occur soon.
President Sarkozy, who is running for re-election, said the raids were intended to "deny the entry of certain people to France" who did not share the country's values.
"It's not just linked to Toulouse. It's all over the country. It's in connection with a form of radical Islam, and it's in agreement with the law," he said.
Sarkozy suggested then that more raids would follow, saying, "There will be other operations that will continue and that will allow us to expel from our national territory a certain number of people who have no reason to be here."
Merah was blamed for the killings of three French paratroopers, a rabbi and three Jewish children ages 4, 5 and 7 in Toulouse and the nearby city of Montauban. Two other people were seriously wounded in the shootings.
CNN's Rachel Ramsay, Tom Cohen and Alex Felton contributed to this report.