The French government and unions planning another demonstration against labour reforms were at loggerheads Tuesday over how to address security fears following the violence that marred a protest last week.
The unions are demanding permission to march in Paris on Thursday, but the Socialist government -- which has mooted the idea of banning protests while the Euro football tournament is under way in France -- insists that a stationary rally would be easier to control.
Interior Minister Bernard Cazeneuve said in a letter to the head of the largest union, the CGT, on Monday that the June 14 unrest "for the first time clearly proved the role of some union activists in deliberate aggression against security forces."
Given the "context of tension and recurrent clashes" another march "seems inconceivable," he added.
Protests against France's hotly contested labour reforms kicked off in March and have frequently descended into violence, notably in Paris and in the western cities of Nantes and Rennes.
Last Tuesday, the violence reached a new peak when marchers bashed storefronts and attacked a children's hospital, smashing some of its windows.
Several hundred masked protesters hurled projectiles at police, who made dozens of arrests.
Two police officers were hospitalised, while another 26 were injured.
After Tuesday's talks the unions said they "categorically refused" to limit the protest to a rally after proposing alternate routes to their planned march.
The police said afterwards: "Talks are continuing and at this stage no decision has been made."
Seven unions had lodged a joint request late last week for permission for a march covering 2.3 kilometres (1.4 miles), a short distance that they said "took into account" security concerns.
But on Monday, Paris police asked them to stage a rally without a march to reduce the risk of clashes.
Faced with the unions' refusal the police said they may be "forced to ban" the protest.
The seven unions responded jointly that the police should "guarantee everyone's safety" and that a rally would be "much more dangerous" than a march.
The day after the June 14 violence, President Francois Hollande threatened to ban demonstrations "if property and people and public property cannot be safeguarded," his spokesman Stephane Le Foll said.
Le Foll noted that the security forces were already overstretched with the Euro and the continuing threat of jihadist attacks.
Earlier, a defiant Prime Minister Manuel Valls vowed to stand firm on the labour reforms despite the mass protests.
Hollande's Socialist government is trying to push through changes to the labour market in a bid to bring down France's stubbornly high unemployment rate.
But critics see the reforms as skewed towards business interests.