BAGHDAD — Three Spanish journalists have been missing for several days in northern Syria, according to a Spanish journalism organization, amid growing fears that they may have been abducted.

The journalists, Antonio Pampliega, José Manuel López and Ángel Sastre, disappeared while working in the city of Aleppo, the president of the Federation of Press Associations of Spain has told Spanish National Television.

Mr. Pampliega, a freelancer, had worked for Agence France-Presse and others in Syria. Mr. López is a photographer. Mr. Sastre has worked in television, radio and print journalism. All had experience in Syria and other war zones.

Aleppo, Syria’s largest city and its industrial center before the war, is divided between insurgent and government zones and is the scene of daily shelling and battles, as well as bombardment with barrel bombs dropped by government helicopters.