BEIRUT -- The families of two Spanish journalists abducted in Syria by an al-Qaida linked group nearly three months ago appealed publicly for their release Tuesday, after failing to make contact with the captors via intermediaries.

Veteran reporter Javier Espinosa, Middle East bureau chief of El Mundo newspaper, and Ricardo Garcia Vilanova, a freelance photographer who was traveling with him, were taken captive Sept. 16 at a checkpoint near the town of Tal Abyad, in the northeastern Raqqa province near the Turkish border.

The two, who have frequently traveled to Syria to cover the fight between President Bashar Assad and the rebels seeking to oust him, were on their way out of the country after a two week reporting trip when they were seized.

Their families had refrained from publicizing the news because they were trying discreetly to make contact with the captors, identified as members of the al-Qaida affiliated Islamic State of Iraq and the Levant. The Associated Press and other news organizations agreed to their request to refrain from publishing news of the kidnapping, until it was publicly announced Monday.

The two men join a long list of journalists who have been kidnapped while covering Syria, which according to press advocacy groups has become the most dangerous country in the world for reporters over the past two years.

"Javier and Ricardo are not your enemy. Please, honor the revolution they protected, and set them free," Espinosa's wife, Monica Prieto, said at a press conference in Beirut, repeating the sentence in Arabic and English.

The two journalists were abducted along with four fighters from the Western-backed Free Syrian Army who were escorting them and taken to facilities belonging to ISIL in Raqqa. The four FSA members were released after 12 days while there has been no word about Espinosa, 49, and Garcia Vilanova, 42.

Jihadi groups with growing muscle are believed responsible for most kidnappings since the summer, but government-backed militias, criminal gangs and rebels affiliated with the Free Syrian Army also have been involved with motives ranging from ransom to prisoner exchanges. Most have taken place in rebel-held territories, particularly in chaotic northern and eastern Syria, where al-Qaida-linked groups hold influence.

Experts say religious extremists pose a particular danger because they kidnap for ideological reasons, and are less likely to negotiate or yield to foreign pressure.

"We believe they are alive and well," El Mundo director Pedro J. Ramirez said at a news conference in Madrid. He said the Spanish government has been aware of the kidnapping since the beginning and has been working for the men's release.

Gervasio Sanchez, a fellow war correspondent who is acting as spokesman for the families, said that while no group had claimed responsibility for the kidnappings, witnesses who had seen the hostages reported that ISIL was responsible. He said the kidnappers had not made any demands.

Ghaith Abdul-Ahad, a foreign correspondent for the Guardian newspaper also serving as a spokesman for both families, said no direct contact has been made with the captors who have refused to negotiate their release.

The New York-based Committee to Protect Journalists says approximately 30 foreign and Syrian journalists are missing and 55 have been killed since Syria's civil war began in early 2011. They include two Swedish journalists who were abducted in Syria late last month as they were trying to leave the country. The group also has documented at least 26 other journalists who disappeared earlier this year but are now safe.

Often media don't report abduction cases at the request of the families or employers. News organizations on a case-by-case basis are inclined to respect such requests, regardless of the identity of the person abducted, if they are persuaded that publication would increase the danger for the victim.

"I personally have never seen a situation like the one in Syria," said Abdul-Ahad, who was jailed in Libya and Afghanistan. "Once you're kidnapped, there's no one capable of making pressure (on the captors)," he said.

Both Espinosa and Garcia Vilanova are award winning journalists who have long standing experience in covering crises and revolutions in the Arab world and beyond. Espinosa has been living in the Middle East for the past 11 years. He is currently based in Lebanon with his wife and two young children.

He was in the district of Baba Amr in Syria's central region during the attack on a media center in 2012 that killed Britain's Sunday Times correspondent Marie Colvin and French photographer Rémi Ochlik, and has since been back to Syria many times.

Garcia Vilanova has been a freelance photographer and video journalist for over 15 years, specializing in conflict and humanitarian crises.

"Despite the risk, we have placed your tragedy before our own lives, with the sole objective of raising the world's awareness on the situation in Syria," said Prieto, herself an award winning freelance journalist who has covered Syria.

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

------

Associated Press writer Ciaran Giles in Madrid contributed to this report.