Morocco on Tuesday deported another group of sub-Saharan African immigrants who had failed in their bid to reach Europe, sending a plane with 140 Senegalese back home on the third such flight.

More planes were expected to take off later Tuesday, some with illegal immigrants from Mali (search).

About 600 Senegalese (search) and another 606 Malians were being temporarily housed in this border town with Algeria ahead of deportation.

The immigrants, many of whom initially slipped across the border from neighboring Algeria (search), have been using Morocco (search) as a gateway to Europe, making their way north in aves there that would give them a foothold on European soil.

Morocco has come under fire for using force to stop attempts by sub-Saharan Africans to rush barbed-wire fences at two Spanish enclaves in northern Morocco. Nearly a dozen Africans have died trying to get to the other side, some of gunshot wounds.

Morocco's communications minister, Nabil Benabdallah, defended the use of force, saying the problem rightfully belongs to the international community.

Morocco is in a no-win situation, Benabdallah said Monday. Previously it was criticized for not doing enough to stem African immigration. "Then, when we used other means, including force, we created some humanitarian problems. It is not possible to fight this problem without causing humanitarian problems," he said.

The drama in this North African kingdom has highlighted the larger problem of illegal immigration that has haunted Europe for decades.

U.N. Secretary-General Kofi Annan (search) said in Geneva on Monday the issue of people moving across borders "will consume far more of our energy in the years ahead."

He said there are about 200 million people living outside their countries today. "What is important is that we don't make a futile attempt to prevent people from crossing borders. It will not work," he said.

Amnesty International (search) on Tuesday criticized the European Union's refugee policy, claiming the 25 member states were focused on keeping people out instead of providing proper protection.

Benabdallah denied claims his country abandoned some immigrants in the desert. However, he said the numbers involved are so large that he could not say for certain if all receive water and food.

Medecins Sans Frontieres, or Doctors Without Borders, said Moroccan authorities last week abandoned 600 to 700 Africans in a desert area near the border with Algeria after Spain expelled them from Melilla and Ceuta. The aid group said it treated at least 50 for injuries, including some apparently caused by rubber bullets and beatings.

Complicating the matter is a camp set up by Africans on the Algerian side of the border. About 1,500 to 2,000 Africans are waiting there to cross, Algerian reporters who visited the camp said.