A video posted online claims to show the bodies of at least some of the seven foreign hostages believed killed by Islamist extremist group Ansaru following their abduction in Nigeria.
The grainy and silent video posted on YouTube, and seen by AFP on Monday, appears to show at least four victims. The images match screenshots released at the weekend along with the claim that the hostages had been executed after their abduction last month.
The 91-second video is titled in Arabic "the death of the seven Christian hostages in Nigeria," while an English statement announcing the executions is copied in below.
It first shows what appears to be four bodies on the ground next to a man standing with a rifle. There are then a series of close-up shots of three bodies.
Britain, Italy and Greece on Sunday said that the claim by Ansaru that it had killed the seven foreign hostages appeared to be true, however there has been no confirmation from Nigerian authorities.
"The claim is unconfirmed, and as long as it remains unconfirmed we will do all that is possible to free them and ensure the safety of their lives," Nigerian Interior Minister Abba Moro told the BBC's Hausa-language service Monday.
"I want us to also think that belief is quite different from confirmation. And maybe the affected countries believe that was what happened, but on its part, the country where it is said to have happened, based on what it sees, is doing the best it can in ensuring the men are freed, who it hopes are alive."
The foreigners were abducted from a construction site of Lebanese-owned company Setraco on February 16 in Bauchi state in Nigeria's north.
Nigerian police last month said the hostages were four Lebanese, one Briton, a Greek citizen and an Italian. A company official later said the Middle Eastern hostages included two Lebanese and two Syrians.
Restive northern Nigeria has seen scores of people killed in Islamist-linked violence, but the hostage executions marked the deadliest kidnapping targeting foreigners in the region in recent memory.
Ansaru, considered a splinter faction of Islamist extremist group Boko Haram, said in its statement announcing the deaths on Saturday that it had carried out the executions in part because of local media reports that said British planes had arrived in Nigeria in recent weeks to attempt a rescue.
A spokeswoman for the Ministry of Defence in London denied Britain had been involved in a hostage rescue mission.
She pointed to Britain's role in assisting the French and the Nigerians in the operation against Islamists in Mali and said it would "not be too far-fetched" to see planes in the area transporting troops and equipment.
In an email statement sent to journalists announcing the kidnapping two days after the abduction, Ansaru said the motives were "the transgressions and atrocities done to the religion of Allah... by the European countries in many places such as Afghanistan and Mali".
However, some analysts caution that such statements are not to be taken at face value and may hide other motives, with a lucrative market for hostages having taken root in the region.
Ansaru has been linked to several kidnappings, including the May 2011 abductions of a Briton and an Italian working for a construction firm in Kebbi state, near the border with Niger.
The victims were killed in March 2012 in neighbouring Sokoto state during a botched rescue operation.
It also claimed the December kidnapping of a French engineer in Katsina state, bordering Niger. The victim's whereabouts remain unknown.
Seven members of a French family, including four children, were abducted last month in Cameroon, and Cameroon authorities said they were then taken over the border into northeastern Nigeria. Their whereabouts also remain unknown.
Ansaru has appeared to focus specifically on kidnapping foreigners, though it has not been known to have claimed the abduction of the French family. France has blamed Boko Haram for the abduction.
Nigeria is Africa's most populous nation and largest oil producer, roughly divided between a mainly Muslim north and predominantly Christian south.