A jihadist group which has carried out a series of attacks on security forces in Egypt's Sinai peninsula has pledged allegiance to Islamic State (IS).
Ansar Beit al-Maqdis announced the move on a Twitter account in Arabic, saying IS promised "a new dawn raising the banner of monotheism".
IS has taken over large parts of conflict-racked Syria and Iraq, declaring a cross-border caliphate.
Ansar Beit al-Maqdis had previously denied allying itself with IS.
The group used the same Twitter account last week to dismiss reports that it had pledged allegiance to the IS leader, Abu Bakr al-Baghdadi.
In its latest pronouncement, Ansar Beit al-Maqdis - or Champions of Jerusalem - made no reference to its previous denial, but said Baghdadi had been chosen by God to set up a new caliphate.
The group promised to "listen and obey" him and appealed to Muslims everywhere to pledge allegiance.
The whereabouts of Baghdadi remain unclear after the Iraqi authorities said on Sunday that he had been wounded in an air strike by US-led fighter jets.
The US is leading a coalition effort providing air support to forces trying to defeat IS on the ground.
President Barack Obama said at the weekend that the battle against IS was entering a "new phase" with the deployment of 1,500 more troops - non-combat advisers - to Iraq.
Ansar Beit al-Maqdis' pledge of loyalty to IS is being seen as a further sign of IS's growing appeal to other Muslim militant groups.
Militants in Sinai have stepped up their attacks on Egyptian security forces since the military's overthrow of Islamist President Mohammed Morsi in July 2013.
Dozens of troops were killed in an attack on an army checkpoint in northern Sinai last month, though it is not clear which group carried it out.
In response to this attack, President Abdel Fattah al-Sisi gave the military extra powers in October to combat militant groups in Sinai.
In its statement, Ansar Beit al-Maqdis called on Egyptians to rebel against President Sisi, who led the overthrow of Mr Morsi and cemented his succession in an election earlier this year.