MADRID (AFP) - Colleagues and relatives of two Spanish reporters kidnapped by Al-Qaeda-linked radicals in Syria said on Tuesday they believed the pair were alive and well and urged their captors to free them.

El Mundo newspaper correspondent Javier Espinosa, 49, and freelance photographer Ricardo Garcia Vilanova, 42, were seized on Sept 16, the latest of scores of journalists captured while covering Syria's civil war.

"We believe they are alive and we believe they are well," El Mundo's director Pedro J. Ramirez told a news conference in Madrid.

A spokesman for the two men's families, Gervasio Sanchez, added: "We are convinced that they are alive. They were alive and well a month ago," the last time their relatives had news of them from witnesses.

El Mundo identified the captors as members of the Islamic State of Iraq and the Levant, a jihadist faction in Syria with roots in Al-Qaeda's Iraqi affiliate.

El Mundo said it had kept the kidnapping quiet until now while it contacted the captors via intermediaries. The kidnappers have still not made any demands.

"Unfortunately, these gestures have yielded no result and we have concluded, the families in agreement with the newspaper, that the time has come to share our concern and indignation" publicly, Ramirez said.

He called for the kidnappers "to immediately free" Espinosa, Garcia and a third Spanish journalist, Marc Marginedas, a correspondent for Catalan daily El Periodico who went missing on Sept 4.

Espinosa's wife Monica Prieto, who is also a prize-winning journalist, echoed the call in a separate news conference earlier in Beirut.

"We believe the Syrian people need our work, and that we must live up to our responsibility," she said.

"But you, as Syrians, also have a responsibility towards all those, Arabs and Westerners, who have defended you."