Morocco, under pressure from Europe to crack down on illegal migration, has begun repatriating 345 Senegalese and Gambians it caught trying to reach Spain's Canary Islands, state news agency MAP said on Thursday.

Moroccan authorities picked up the migrants in Atlantic waters off Western Sahara and held them in the territory's southern port of Dakhla. A first group of 120 was sent home early on Thursday and 225 more will leave by Saturday, MAP said.

"These operations are taking place in the presence of Senegalese and Gambian diplomats," it said.

A Malian migrant in Dakhla contacted by telephone said he and 116 others had been told they might be sent home next week.

More than 30 000 migrants arrived in the Canaries last year after dangerous boat trips from West Africa, and many more are believed to have died during the crossing.

The number reaching the Canaries has dropped sharply this year since the European Union gave Morocco 67-million euros to manage migration and boost border security. Much of the money goes to tightening coastal patrols.

Barbed wire fences around Spain's North African enclaves of Ceuta and Melilla have been reinforced and a new radar system now scans the waters between Morocco and Spain.

Morocco says the new measures have allowed it to stop over 9 000 attempts at illegal migration -- a third of them towards the Canary Islands -- and break up 260 trafficking gangs.

The number of illegal migrants arriving in the Canaries from Morocco has fallen 91% in two years, it said.

But with few reasons to stay in their poverty-ridden countries, thousands of sub-Saharan Africans are still trekking through the desert to Mauritania and Morocco and paying unscrupulous traffickers for passage north on overcrowded boats.

Morocco has deported thousands of the migrants. Aid groups accused it last year of dumping hundreds, including women and children, on the desert border with Algeria without food or water.

The Moroccan government says the migrants are treated well and given food, water and health care before being sent home.