The European Commission voiced concern on Tuesday over the Niger military government's scrapping of a law on migrant trafficking, saying it could increase the number of people trying to reach Europe irregularly.

"I'm very concerned about the situation now, and there is a huge risk that this will cause new deaths in the desert," European Union home affairs commissioner Ylva Johansson said, referring to the Sahara.

She said it "would also probably mean more people coming to Libya, for example, and then maybe also trying to cross the Mediterranean to the EU".

The head of Niger's military government, General Abdourahamane Tiani, on Saturday signed an order repealing the 2015 law, which had sought to curb the number of West African nationals travelling through the Sahara and then on to Algeria or Libya in a bid to eventually reach Europe.

The law, arranged under the previous civilian government, had been backed by EU money.

It involved increased surveillance of the desert, which many migrants sought to circumvent by using more dangerous alternative routes.

"I very much regret" the decision by Niger's rulers, Johansson said, underlining the "very, very close cooperation" the EU had had with the Sahel country's previous government.

Brussels has condemned the coup on July 26, when the military ousted the civilian government and detained elected president Mohamed Bazoum at his residence.