An Islamist militant group has claimed responsibility for Saturday's attack on a Chinese-owned container ship passing through the Suez Canal, a global waterway between Asia and Europe.
Kataeb Al-Forqan released a 51-second video on Thursday showing two gunmen targeting rocket-propelled grenades at a passing ship, Panamanian-registered COSCO Asia.
The footage was emblazoned with an Al-Qaeda flag with the group's name added at the bottom. One of the assailants cheered "Allahu Akbar" (God is Greatest) as they fired at the vessel.
Suez Canal Authority head Mohab Mamish said the attack had "failed completely and there was no damage to the ship or the containers it carried."
On Sunday, an army source said authorities had arrested three people who opened fire with machine guns on the ship.
In an online statement, the group said it claimed responsibility for "targeting the international shipping waterway which has become a safe route for crusader aircraft carriers travelling to attack Muslims, and a trade artery for infidel and tyrannical states."
The attack has heightened threats to shipping through the 92-kilometre waterway, a major source of national income that generates about $5 billion a year in tolls.
Egypt has been rocked by political turmoil since Islamist president Mohamed Morsi was ousted by the army on 3 July in what his supporters called a "military coup." More than 1,000 people, including 100 security officers, have been killed in street violence since Morsi's ovethrow, the bloodiest unrest in the country's modern history.
A wave of arrests has netted the top leaders of Morsi's Muslim Brotherhood and least 2,000 other Islamists.
The statement condemned what it termed the "coup against Islam and its people," yet tacitly slammed Morsi's Brotherhood when referring to those who gave "legitimacy to [ballot] boxes, not Allah and his prophet."
"We promise Muslims that we are preparing for knock out strikes against the regime, and its institutions," the statement titled 'Democracy is Infidelity' added. "The coming is more severe and bitter."
The armed forces have tightened up security measures along the Suez waterway, officials say.
Egypt's army is already battling an upsurge in militant activity by hard-line Islamists in the nearby Sinai Peninsula since Morsi's exit. At least 25 policemen were killed there in an ambush last month.