Japan's government said Monday it was investigating a video posted online that appears to show a kidnapped Japanese man being roughly interrogated by Syrian militants.
The video, which surfaced over the weekend, shows a man who identified himself as Haruna Yukawa lying on the ground with blood trickling down his face as his apparent captors question him.
The man, with matted brown hair and wearing a black T-shirt stained by dust and sweat, offered brief responses to questions posed in English about why he was in Syria and the reason he was carrying a gun.
He replied in stilted English that he was a "photographer" and a "journalist, half doctor", as his interrogators accused him of lying, with one placing a long knife near his chest before the video stops.
"I'm no soldier," the man said in the video as apparently dubbed on Middle-Eastern music played.
Japan's foreign ministry said it was trying to verify the man's identity through its embassy in violence-wracked Syria, which is now operating out of neighbouring Jordan.
"We are gathering all available information available, including on social media such as Facebook and Twitter, but we have to be cautious about the credibility of that kind of information," a ministry official told reporters.
"We need to confirm facts around the case."
Some messages on social media referred to Yukawa as a spy, and said he had been executed by Islamic State (IS) militants.
The foreign ministry was "not in a position to directly contact" the group, the official said.
"We are trying to make a contact with them in any way we can," he added.
No one has claimed responsibility for the apparent kidnapping.
- 'Private military firm' -
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Vice foreign minister Akitaka Saiki later told reporters that the civil war in Syria made it difficult to investigate the case.
"Syria is in a very confused state and we are seeking to confirm the safety of the person through various routes," he said.
Since 2011, Japan has been recommending that its nationals stay away from the strife-torn country.
The foreign ministry as well as the prime minister's office and National Policy Agency have set up a special team to deal with the incident, the ministry official said.
But he declined to confirm the identity of the person on the video, or even if a person named Haruna Yukawa was missing.
"Because of the situation in Syria, we don't have any staff in the country and we have no plan to send anyone," he said.
Early last year, a Japanese trucker who entered Syria clandestinely through Turkey made headlines as a war tourist who said he was shooting photos and video of conflict.
Another online video that appeared at the weekend showed a man believed to be Yukawa test-firing an AK-47 assault rifle in Syria.
The video can also be seen at the website of Tokyo-based private military firm PMC, which lists Yukawa as its chief executive. Pictures on the website, which kept crashing Monday afternoon, show him with right-wing Japanese activists.
Details about the kind of services the firm offered were not immediately available.
Calls to the firm went unanswered on Monday and it was unclear if the company had other employees. Its website said the firm has branch offices in "Turkey, Syria, Africa".
There was no evidence of the company at the Tokyo address given on the website, a 13-storey office building.
Yukawa also has a blog with video footage of what he describes as massacres in the northern Syrian city of Aleppo by President Bashar al-Assad's forces.
Japanese nationals' involvement as combatants in foreign conflicts is limited, although the country's extensive media is usually well-represented in hotspots.