An Al-Qaeda-inspired group based in the Egyptian Sinai threatened Thursday to attack contractors and workers involved in the construction of a security wall at a town in the restive peninsula.

The Ansar Beit al-Maqdis (Partisans of Jerusalem) group has claimed most of the deadliest attacks in Egypt since the military ousted Islamist president Mohamed Morsi in July, saying they were in revenge for a crackdown on his supporters that left hundreds dead.

In a statement published on jihadist forums, the group accused authorities of building a wall around the town of Al-Arish, in north Sinai, to "isolate it from other villages and towns of the province", threatening to carry out attacks against those involved in the project.

"We warn contractors, investors, owners of companies, workers, those who are supervising the construction of this wall, owners of trucks transporting building materials: we won't neglect targeting you and we will spare no effort... to prevent you," the group said.

Security officials denied the construction of a barrier around Al-Arish, but said authorities started weeks ago to build a wall south of the town to secure the airport and nearby agricultural fields used by militants as hideouts.

The army has poured troops into the mountainous and underdeveloped Sinai peninsula, which borders the Palestinian Gaza Strip and Israel, to combat the growing militancy.

Most of the attacks have been carried out in the northern Sinai and have targeted soldiers and policemen, but militants have lately expanded their reach to the Nile Delta.

In recent months, Ansar Beit al-Maqdis has claimed responsibility for a car bombing at a police headquarters in Cairo, the shooting down of a military helicopter and the suicide bombing of a tourist bus in the Sinai.

More than 1,400 people have been killed in the security forces' crackdown on Morsi's supporters, according to Amnesty International. Thousands have been jailed.