Egypt arrests three after gun attack on ship in Suez Canal: source CAIRO (Reuters) - Egypt has arrested three people who opened fire with machine guns on a ship passing through the Suez Canal, an army source said on Sunday, playing down what the waterway's chief described as a terrorist attack. During Saturday's unsuccessful attack, the Panamanian-registered container ship COSCO ASIA came under fire in a northern section of the canal, a major global trade artery which is secured by the Egyptian armed forces. "There was an attempt to disrupt security in an area called el-Qantara as they fired at a ship in an attempt to halt (traffic on) the waterway," said the army source. Three were arrested and they have been dealt with ... This attack could not have harmed the ships," the source said, without giving any details except that an investigation was underway. On Saturday, the head of the Suez Canal, Mohab Memish, said a terrorist had carried out the operation, suggesting Islamist militants could have been behind it. Suez Canal Authority sources said a rocket-propelled grenade had been used in the attack. The sources said that even if a grenade had struck the ship, it would have had a limited impact. The aim, they said, was to create a media frenzy and hurt Egypt's image. Asked if the military suspected the attack was part of a broader campaign to disrupt the movement of ships, the army source said. I don't think so because the Suez Canal is secured. Any major attack on the Suez Canal would hammer Egypt's economy, which depends heavily on revenue from the 192-km (120 mile) waterway, the quickest sea route between Asia and Europe. Egypt has faced a rising number of militant attacks on security forces in the nearby lawless North Sinai region after the army, prompted by mass protests, ousted the country's first elected Islamist President, Mohamed Mursi, on July 3. Growing insecurity in Sinai worries the United States because the area lies next to Israel and the Hamas-ruled Gaza Strip, as well as the Canal. The Suez Canal Authority has received threats from unidentified groups which said they would target the waterway, security sources said. At one point the military blocked a bridge over the canal as a precautionary measure because of threats. On July 30 the Egyptian army investigated reports of an explosion heard near the Suez Canal but found no evidence of a blast after scanning the area. Editing by Michael Georgy and David Stamp