(CNN) -- A U.S. journalist missing in Syria for nearly six months is most likely in Syrian government custody, according to the GlobalPost, an online international news outlet, and the man's brother.
Gunmen kidnapped James Foley on November 22 and his family has since worked to obtain his release. Foley, a free-lance journalist, contributed stories to the GlobalPost.
According to a GlobalPost story on Friday, its CEO and president, Philip Balboni, said in a speech marking World Press Freedom Day that the outlet has a "very high degree of confidence" that Foley was "most likely abducted by a pro-regime militia group and turned over to Syrian government forces."
"We have obtained multiple independent reports from very credible confidential sources who have both indirect and direct access that confirm our assessment that Jim is now being held by the Syrian government in a prison or detention facility in the Damascus area," Balboni said.
"We further believe that this facility is under the control of the Syrian Air Force Intelligence service. Based on what we have learned, it is likely Jim is being held with one or more Western journalists, including most likely at least one other American."
Another American journalist, Austin Tice, also is missing in Syria.
According to the report, Balboni said that GlobalPost representatives were meeting with the Syrian ambassador to Lebanon in Beirut to muster support. The ambassador has delivered letters to the Syrian ministries of defense, interior, information and foreign affairs, GlobalPost said.
Michael Foley, James Foley's brother, told CNN that information from "highly credible sources" indicates that "the Syrian government is holding him right now." He wouldn't elaborate.
The Syrian government, however, has so far not acknowledged knowing of Foley's whereabouts.
"We continue to explore all avenues privately and through diplomatic channels to convince the Syrian government to release Jim so that he can return to his family," Balboni said. "We remain hopeful and totally committed to bringing Jim Foley home safely and as quickly as possible."
GlobalPost said Foley was in a car heading for the Turkish border when, an eyewitness said, an unmarked car intercepted the journalist.
"The witness said men holding Kalashnikovs shot into the air and forced Foley out of the car. That was the last anyone heard from him," GlobalPost reported.
Foley was taken along with others in Libya in 2011. He and three other journalists were released by the Libyan military in May 2011.
CNN's Pauline Kim contributed to this report