CAIRO (Reuters) – Gaza militants may be behind rockets that hit Israel and Jordan on Monday, Egypt’s official news agency quoted a security source as saying on Wednesday.

“The preliminary information that the security has received indicates that Palestinian factions from the Gaza Strip are behind that operation,” the unnamed Egyptian source told the state MENA agency.

Rockets from Egypt’s Sinai, where Islamist militants have operated in the past, hit Israel’s and Jordan’s Red Sea ports, killing a Jordanian civilian and injuring three others, Jordanian and Israeli police said.

“Egypt will not accept the use of its land by any party to harm Egyptian interests,” the Egyptian security source said, adding that authorities were scaling up their investigation.

Egypt earlier denied the rockets came from Sinai. No group has claimed responsibility for the attack.

MENA quoted Egyptian security sources on Monday as saying rockets could not have been fired from Sinai since the largely empty, desert region was very mountainous.

In 2005, rockets were fired at U.S. warships in Aqaba but missed their target and killed a Jordanian soldier on land. A group claiming links to al Qaeda said it was behind the attack.

Two years later, a Palestinian suicide bomber infiltrated through Sinai and killed three people at a bakery in Eilat, a tourist resort on Israel’s southern tip which has only rarely been touched by the Middle East conflict.

Jordan and Egypt are the only Arab states to have full peace treaties with Israel. Those relations were frayed by Israel’s crackdown a decade ago on a Palestinian uprising in the West Bank and Gaza Strip.