The French government has made its first sign of giving ground to teenage protesters, with a promise of 3,000 extra supply teachers in the coming days.

Education minister Edouard Geffray made the offer in a television interview on Thursday evening, at the end of another day of sometimes violent demonstrations by high-school students.

The government says 6,877 people have been arrested, 86% of whom are under the age of 18, since protests began centred around demands for more resources in secondary education.

In what unions have billed as Act Four of the three-week movement, some 71,000 people staged protests across the country on Thursday, with 24,000 gathering at the Bastille in Paris.

Police once again intervened with tear-gas to disperse groups who attacked them with paving stones and homemade fireworks.

In Bordeaux, a lycée, or high school, was ransacked by protesters, and in Marseille a deputy-head was beaten up.

On Friday, some 140 lycées – out of 3,500 – were totally or partially closed, a big drop on previous days. But another day of action has been called for next Tuesday.

Geffray’s announcement was the first material concession to the protesters’ complaints.

It has long been recognised by all concerned in French education that too many school hours are being lost because of absent teachers and their non-replacement by available supply staff.

The minister said that thanks to new software coming online at the ministry, it would be possible to direct 3,000 supply teachers to the 500 or so lycées identified as being in the greatest need.

Many of these schools are likely to be in high-immigration city suburbs, where the lack of teachers is most acute.

Geffray also said that more money would be made available under an already existing scheme for those teachers who want to work overtime hours in order to plug gaps.

And he promised that students’ grievances would be taken into account in forthcoming discussions on the education section of the 2027 state budget.

But the offer contained no major promise of new investment on a scale likely to appease protesters.

The government is wary of appearing to buy social peace because it knows France’s precarious debt situation is being followed closely by international money markets.

Reaction from student leaders has been guarded to say the least.

Nathanaël Combary, who represents the most moderate of the three main lycée unions Renouveau Lycéen (Lycée Renewal), said students were waiting to see how the promise was carried out in practice: “We’ve had some announcements which correspond to part of our demands. But obviously people want to see the money and more concrete results.”

“As long as we do not have €10bn on the table, we will continue our action,” said Sabrine Kharbach of the Union Etudiante (Student Union), which is close to the radical-left France Insoumise (France Unbowed) party of presidential candidate Jean-Luc Mélenchon.

Mélenchon praised Thursday’s demonstrations, saying on X that the students had “retaken the Bastille”.

But at the other end of the political spectrum, a spokesman for the hard-right National Rally (RN) condemned the government’s concessions.

“The message is: if you break things, you get given stuff,” said Laurent Jacobelli. “When you burn cars, attack police, you gain something in return. It’s the legitimisation of violence.”

The movement is the most serious student unrest in France in many years, and comes against a backdrop of rising tension in the country – with anger over rising fuel prices and distress in the farming sector also liable to trigger protests.

Next Saturday, 17 October, has been earmarked as a day of demonstrations by a revived “yellow vest” movement.

In addition, the approach of presidential elections in April and May – in which both hard right and hard left are expected to perform strongly – is exacerbating the mood of confrontation.

The government is hoping that the approach of half-term holidays at the end of next week – as well as the arrival of colder and wetter weather – will take some of the sting out of the protests.