Hundreds of thousands of protesters took to the streets across France on Tuesday, including in the capital Paris

France has suspended the use of stun grenades for policing student protests that have swept the country, after a 15-year-old's hand was blown off earlier this week.

Interior Minister Laurent Nuñez said he had requested the pause until the facts of Monday's incident in Lens had been "clarified", with conflicting accounts offered by protesters and officials.

Several groups have complained of police using disproportionate force towards teenagers.

The disruption continued early on Wednesday with more than 500 schools fully or partially shut, and Prime Minister Sébastien Lecornu is due to speak about the school protests in an evening address.

Education Minister Édouard Geffray said 24 schools had been "set alight or vandalised" to such an extent that they would be shut for several weeks, affecting 30,000 pupils.

Hundreds of thousands of people took to the streets on Tuesday to call for better school conditions and in some cities tear gas and water cannon were deployed. The interior ministry said 488 people were arrested and 43 members of the security forces were hurt.

Nuñez told French radio RTL that police watchdog IGPN had opened 18 investigations to determine whether officers had been "proportionate" during the demonstrations, which have spread from high school pupils to their parents, university students and unions.

Watch: Why has the use of stun grenades been suspended during the student protests?

"There is a police action that raises questions for all of us within the Ministry of the Interior; it's what happened in Lens," he said as he confirmed the suspension of stun grenades - weapons which are considered non-lethal and send out small rubber pellets when they detonate.

The 15-year-old boy's hand was torn off after a so-called anti-encirclement grenade was fired in unclear circumstances near the Auguste Béhal high school in the northern city near Lille.

Authorities have said he picked up the grenade which then exploded, but students have alleged he was hit directly after an officer fired. According to the local prefect, police had been confronted by more than 200 students throwing stones and fireworks.

The national secretary of policing union UNSA said he was sceptical about the move, saying it had been based "on emotion".

"We are dealing with increasingly violent people," Jean-Paul Nascimento told FranceInfo, cautioning that without the weapon to disperse crowds there may be more clashes at close quarters. "That's where there will perhaps be even more injuries," he warned.

Protests were largely peaceful on Wednesday, but tensions flared near Paris's Sciences Po university as officers used tear gas and pushed protesters back along a barricaded street

Concerns have also been stoked by the case of a 14-year-old hit in the face with a tear gas grenade last week. The boy's lawyer said he had lost several teeth and suffered a fractured jaw in the incident at Saint-Ouen-l'Aumône, north-west of Paris, and a police officer has been charged.

And in a separate development on Wednesday, a 16-year-old suffered a serious hand injury outside a school in Strasbourg, reportedly while handling a mortar firework.

Prosecutors also said an investigation for attempted murder had been opened after a 17-year-old student protester complained an officer "held his head underwater" while trying to arrest him near a river in the north-eastern city of Belfort. French reports say the boy has himself been charged with aggravated assault for allegedly attacking the officer.

Addressing France's National Assembly on Wednesday, both Nuñez and Education Minister Geffray said the speed at which the protests had turned violent was unprecedented.

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Geffray said dozens of headteachers and deputies had been injured, many deliberately so, and alleged the movement had been "very quickly infiltrated by ultra-violent groups".

"We have never seen anything like this," he said of the disorder which officials report has harmed more than 200 students and 700 police officers, and prompted more than 6,600 arrests.

Nuñez later said he found it "excessive to speak of police repression of the movement", insisting that officers were only acting in response to violence and damage.

The national coordinator of the radical-left France Unbowed (LFI) party said that it had taken "several children being maimed for life for Nuñez to give up using grenades against high school students".

The prime minister has accused LFI of trying to "sow chaos" during the protests ahead of elections to select President Emmanuel Macron's successor in April.

Its leader Jean-Luc Mélenchon is currently second in the opinion polls behind Marine Le Pen of the hard-right National Rally - who on Wednesday said Macron was "always on the side of attacking the police".

The president held an emergency meeting late on Tuesday with Prime Minister Lecornu and other key ministers to find a way out of the crisis after almost a quarter of all lycées were disrupted by the day's protests - with government figures putting the number of protesters at more than 250,000.

Lecornu announced that schools should set aside half the day for students to voice their concerns, and noted on social media that an online consultation seeking their opinions had drawn 30,000 responses within a day.

But students' unions - who put the number of protesters at 450,000 - maintain a fourth round of demonstrations is planned for Thursday in Paris and other cities, and told reporters they had requested a meeting with Lecornu due to a lack of "concrete measures" outlined so far.

The union representing school leaders told FranceInfo that a solution would require "something more than simple consultation periods", while the head of the USL high school union, Ryad Rani, told French radio on Wednesday: "We are telling M. Nuñez, calm your police officers down and call for restraint."