Tunisia has moved hundreds of migrants to shelters in two towns, a local rights group said on Tuesday, after criticism of conditions in a desolate Sahara military area on the border with Libya, where the government transferred them last week.

“Hundreds of people who were on the Libyan border were transferred finally to shelter centres in Medenine and Tataouine towns after difficult times they spent there in the intense heat”, Ramadan Ben Omar, an official at the non-governmental Tunisian Forum for Economic and Social Rights, told Reuters.

Tunisia's interior ministry did not respond to a request for comment.

The government moved the migrants to the site at the Libyan border following an outbreak of violence in the coastal city of Sfax earlier in July.

The disturbances between migrants and residents in Sfax lasted a week and one Tunisian was killed. Residents complained of disorderly behavior by migrants and migrants complained of racist harassment.

Thousands of undocumented migrants have flocked to Sfax in recent months with the goal of setting off for Europe in boats run by human traffickers, leading to an unprecedented migration crisis for Tunisia.

While overall irregular migration to Europe is up about 12% this year, it more than doubled in the central Mediterranean region, according to data from Europe’s border agency in May.

Tunisia is now under pressure from Europe to stop migrants departing from its coasts. European countries are considering a package of financial support to help the economy and to deal with migration.