The Spanish government has repatriated more than 750 African migrants, including 30 children.
The Canary Islands are struggling with an influx of African migrants
The majority were Senegalese and were caught last week trying to enter the Canary Islands, according to Spain's interior ministry.
The government said all illegal immigrants would be expelled.
The latest influx is blamed on the temporary suspension of maritime patrols between the Spanish islands and the western coast of Africa.
The Spanish Interior Minister, Alfredo Perez Rubalcaba, confirmed the migrants had been returned home.
"We have repatriated, with the invaluable help of the government of Senegal, nearly 600 citizens of that country," he said. "This is an unmistakable message to the mafias."
Traffickers often extort money from Africans trying to reach Europe via hazardous sea crossings to the Canaries.
No information was given about where in Africa the other migrants had come from.
Overall this year, though, the numbers of would-be immigrants are down compared to the same time last year.
In 2006 an estimated 30,000 immigrants were caught trying to reach the Canary Islands.
The vast majority sailed from west Africa in crowded open boats, many dying en route.
The European Union's external borders agency, Frontex, suspended maritime patrols around the Spanish islands early last month, when its 2006 mission ended.
The patrols are expected to restart within weeks, after the agency receives equipment including planes, helicopters and boats.