A growing number of Syrians are flying to Mauritania before making long and dangerous journeys through the Sahara Desert toward Europe, and more may follow as European nations restrict entry at their land borders, experts said Thursday. Hundreds of Syrians have registered as refugees or asylum seekers in the West African nation this year, but many do not register and the number flying to the capital Nouakchott on their way to Europe is probably far higher, experts say. Thousands of Syrians have applied for asylum this year in Morocco's Spanish enclaves of Ceuta and Melilla. Most used to fly from Beirut to Algiers and cross the border to reach the two popular gateways to Europe. Algeria imposed visa restrictions on Syrians earlier this year, diverting many to Mauritania from where they travel on through Mali, Algeria and Morocco, the International Organization of Migration said. Many Syrians are also trying to reach Sicily from Tunisia and Libya via Agadez, a desert town and main transit point in Niger for migrants, where people smuggling is rife. "There has been an increase in movement in 2015 since the introduction of visas for Syrians in Algeria in March – that was the turning point," IOM representative Anke Strauss said. More than 800,000 asylum seekers and migrants have crossed the Mediterranean this year, half of them Syrians, and the number is expected to top a million by end-year, the U.N. refugee agency has said. The vast majority of those entering Europe this year have traveled via Turkey to Greece, a switch from the previously more popular African route via Libya to Italy. But flying to West Africa and crossing the Sahara may become more common as European nations tighten controls and close borders, said Sebastien Laroze, Mauritania representative for the UNHCR. Populist leaders in Europe demanded an end to the influx of refugees and migrants Saturday after a wave of deadly attacks in Paris claimed by ISIS militants, and Sweden last week imposed its first major border controls in two decades. Around 300 Syrian refugees and asylum seekers are living in Mauritania, and around one in 10 of them have tried to cross into Mali and head for Europe, Laroze said. Syrians heading for Europe do not register with agencies in Mauritania, the UNHCR said, so the number crossing the Sahara is unclear. "We are informing Syrians of the situation across the region and ensuring they are aware of the dangers," Laroze added. At least as many migrants could die of hunger and thirst in the Sahara as drown in the Mediterranean, the IOM warned earlier this year. Its latest figures show that more than 3,500 people have died or gone missing at sea in 2015.