The Islamist militant group Ansar Beit Al-Maqdis, which has been waging an insurgency against the Egyptian army, claimed in an audio recording released online on Wednesday that it was responsible downing the Russian plane over Sinai on Saturday.
The group, which pledged allegiance to ISIS in 2014, however, cited no evidence to support their claim, failing to provide information on how they downed the Airbus A321, which crashed early Saturday in central Sinai, killing all 224 people on board.
"We are not obliged to prove anything or to reveal what we used to down the plane," said the three-minute audio message recorded in Arabic.
The recording suggested that officials check the plane's black box to determine how it was downed.
The message's unknown narrator claimed that the militant group downed the plan on the anniversary of its pledge of alliance to ISIS leader Abu Bakr Al-Baghdadi.
Egypt, along with Russia, France -- which manufactured the plane -- and Ireland -- where the plane was registered -- is conducting an investigating into the cause of the crash.
Hours after the crash of the plane, which was on its way from Sharm El-Sheikh to St Petersburg, the terrorist group released a written statement in seven languages on pro-ISIS twitter accounts saying that it downed the flight in retaliation against Russian airstrikes in Syria.
However, the group's claim that it was responsible for the crash has been disputed by several officials, including Russia's Minister of Transport Maxim Sokolov, who told Interfax news agency that claims of the flight being downed by terrorists "cannot be considered accurate."
In an interview with the BBC, Egypt's President Abdel-Fattah El-Sisi also dismissed the claim, saying it was terrorist propaganda.
The US State Department and the US director of national intelligence said they had not seen any evidence supporting the claim of Ansar Beit Al-Maqdis.
The militant group has claimed responsibility for most of the attacks against Egyptian security forces in North Sinai as well a number of terrorist attacks across Egypt since August 2013.