Egyptian Soldiers, Rafah, Oct. 30, 2014
Egyptian soldiers keep guard during a military operation in the Egyptian city of Rafah, near the border with the southern Gaza Strip Oct. 30, 2014. Reuters/Ibraheem Abu Mustafa

Update as of 5:50 a.m. EDT: Militants of Ansar Bayt al-Maqdis, or ABM, dismissed reports, which emerged earlier on Tuesday, that the group has pledged allegiance to the Islamic State group, just hours after doubts were raised over the veracity of an earlier statement attributed to them.

“This is not the first time that false statements have been attributed to Ansar Bayt al-Maqdis, and this probably false report may be related to the group's recent prominence in conjunction with the suicide attack targeting Egyptian security forces in the Sinai,” according to a report by the Washington-based Institute for the Study of War. “Egypt is facing real and very serious threats emerging from its territory, but Ansar Bayt al-Maqdis joining forces with ISIS is not yet one of them.”

Sinai-based Ansar Bayt al-Maqdis, believed to be the most active militant group in Egypt, declared its support for the Islamic State group in a statement released late Monday, according to media reports. In doing so, the group broke off ties with al Qaeda, which has previously referred to ABM's members as “our mujahideen brothers in Sinai.”

“After entrusting God, we decided to swear allegiance to the emir of the faithful Abu Bakr al-Baghdadi, caliph of the Muslims in Syria and Iraq and in other countries,” ABM reportedly said, in the statement.

The decision by the jihadist group’s leadership to pledge allegiance to the Islamic State group is expected to significantly expand the latter’s sphere of influence, which, so far, has no presence in Egypt.

ABM first emerged in 2011 amid a security vacuum created by the ouster of former Egyptian President Hosni Mubarak. The group is believed to be based in the northern Sinai desert, close to the Israeli border. It is also believed to have some presence in the Gaza Strip, where it reportedly functions as a rival to Hamas.

There has been a drastic uptick in the group’s activities since the removal of Mohammed Morsi in 2013 and a number of attacks targeting Egyptian security forces have been attributed to the group. Most recently, ABM was believed to be behind last month’s attacks on two army checkpoints in northern Sinai, which killed over 30 soldiers.

The announcement by ABM comes less than two months after two of al Qaeda’s most powerful branches -- Al Qaeda in Arabian Peninsula and Al Qaeda in Islamic Maghreb -- reportedly offered their support to ISIS, describing the group as the "Muslim brothers in Iraq against the crusade."