A Syrian man claiming to be the mediator negotiating the release of abducted Japanese journalist Jumpei Yasuda has decided to end his involvement in the case, saying the government has not responded to the captors' demands.

In a statement released on another Syrian's Facebook account Wednesday, the man said he had failed in his attempt to mediate talks to help free the 42-year-old freelance journalist. Yasuda, who went missing in Syria last year, is still believed to be held by the militant Nusra Front, al-Qaida's wing in Syria. The group is reportedly seeking a $10 million ransom.

While the Facebook post said Yasuda's current condition was not known, the Syrian mediator said he could no longer ensure Yasuda's safety.

A photo of a bearded Yasuda holding a sign in Japanese saying "Please help. This is the last chance" was posted on a social-networking site on May 29. The hostage-takers had said that Yasuda would be handed over to the Islamic State group unless the government begins negotiations within a month. That time frame was set to expire Thursday.

Yasuda went missing after entering Syria from neighboring Turkey last June. Video footage of him reading a message to his family was posted on Facebook in March.