France, Spain join forces in wake of terror attacks

France's interior minister on Wednesday said his country was working closely with Spain to determine why some of the men suspected of last week's deadly terror attacks in Catalonia visited the Paris region two days beforehand.

Gerard Collomb met his Spanish counterpart Juan Ignacio Zoido days after terrorist attacks on Las Ramblas in central Barcelona and another vehicle incident in the Catalan town of Cambrils killed 15 people and injured 100 more.

Four of those accused of the attacks appeared in a Madrid high court on Tuesday.

Speaking at a news press conference in Paris, Collomb said France and Spain were "working to determine why the authors of the attacks came to Paris and what they did in the Paris region".

Collomb has previously said an Audi used by the attackers in Cambrils had been flagged for speeding outside Paris, without giving any further details.

"We know what difficult times Spain has just crossed with these attacks in Barcelona and Cambrils," he said.

"But today we see that the cooperation between the different European countries is more necessary because the perpetrators of the attacks know no borders... if we do not coordinate our forces we will not be able to prevent ... attacks, or arrest their perpetrators," Collomb added.

The two ministers also signed plans for a joint eight-month training program for 120 French gendarmes in Spain.