The US has said it will "assess" the potential implications of an Egyptian jihadist group's pledge of allegiance to Islamic State (IS).
US Department of State spokesperson Jen Psaki said on Monday that her country needs to look into what it means for Sinai-based Ansar Bayt Al-Maqdis to swear loyalty to IS.
IS has taken over swathes of Syria and Iraq and is currently facing US-led strikes.
"[We have to assess] whether the sworn allegiance means affiliation, whether it means action, whether it means they’re joining the effort," she said.
The US remains concerned about the "strength that [IS has] developed over the last several months," which has prompted the formation of a coalition with ten Arab states to confront it.
The Egyptian army, which is carrying out a major operation against an expanding jihadist insurgency in Sinai, has not yet commented on the issue.
There has been mounting speculation that militant groups in Sinai are establishing relations with IS.
On Monday, Ansar Bayt Al-Maqdis, which has previously claimed responsibility for several attacks on Egyptian police and military forces, released an audio-clip pledging allegiance to IS leader Abu Bakr Al-Baghdadi.
Egypt is part of the US-led coalition against IS. However, Egyptian officials have thus far said that the country’s military will not take part in any combat abroad against IS and shall confront it using other means, including cutting funding sources and offering an alternative religious discourse.