An Egyptian militant group that pledged allegiance to the ISIL terrorist group last month has claimed it was behind the killing of an American oil worker in August.

An Egyptian militant group that pledged allegiance to the ISIL terrorist group last month has claimed it was behind the killing of an American oil worker in August.

"We claim the murder of American oilman William Henderson in the Western Desert" of Egypt, Ansar Beit al-Maqdis said on Twitter.

The message was accompanied by pictures of Henderson's work identity cards and his passport, without providing any more details.

Egyptian security sources contacted by AFP on Monday said police had received information that 'jihadists' had killed Henderson in August.

Henderson, who worked for the US oil company Apache, was slain near his workplace in the Western Desert, the sources added.

According to US media reports that cited Henderson's obituary and employer, the 58-year-old had been killed in a carjacking while working in the Karama oil field on August 6.

Ansar Beit al-Maqdis, which pledged allegiance to ISIL in November, is based in the Sinai Peninsula and has been designated a "terrorist organisation" in Egypt.