Eric Dupont-Moretti, lawyer of Abdelkader Merah, brother of Islamist militant Mohammed Merah, who killed 7 people in 2012, and who stands accused of complicity in the series of shootings committed by his brother, arrives for the verdict in Abdelkader Merah's trial at the courthouse in Paris, France, November 2, 2017. REUTERS/Gonzalo Fuentes

PARIS (Reuters) - The brother of a French Islamist who shot dead seven people in 2012 will face an appeal against his acquittal on charges of conspiracy to murder, Paris prosecutors said on Friday.

Abdelkader Merah, the brother of Mohamed Merah, who was killed in a police raid on his Toulouse apartment soon after the attacks, was jailed for 20 years on Thursday for associating with terrorists, but cleared on the conspiracy charge.

That verdict was criticized by relatives of the murder victims - three soldiers and four Jews, including three children - as well as prosecutors who allege that Abdelkader was more than just a religious mentor to his younger brother.

France’s special terrorism court found there was insufficient evidence that he had knowingly aided his brother’s eight-day killing spree. Announcing their appeal, prosecutors said the court had failed to “draw the full legal conclusions of the evidence put before it”.

Such an appeal would typically take years to come to court, but judicial authorities are facing calls to fast-track the case, which is closely watched for the precedent it may set for other terrorism prosecutions.

“This is a benchmark terrorism case, particularly for trials of accomplices in the absence of the main perpetrator,” said lawyer Simon Cohen, who represents families of Mohamed Merah’s victims. “And there will be more of those.”