Two military-grade rockets struck Jordan early on Thursday, one slamming into an empty warehouse in Aqaba and the other splashing into the Red Sea near the Israeli border, a security official said.
"The preliminary investigation determined that the explosion in the (Red Sea) port of Aqaba on Thursday morning was due to a Katyusha rocket," the security official said, citing sources close to investigators.
"A second Katyusha rocket was found in Jordanian territorial waters," he added, speaking on condition of anonymity.
Prime Minister Samir Rifai later said the authorities were "100 percent sure" the rocket that hit the warehouse, which he said was a Grad-type projectile, had not been fired from Jordanian territory.
Information Minister Nabil Sharif, speaking of the explosion at the refrigeration warehouse on the outskirts of Aqaba, said it had caused "no casualties and minimal damage."
Authorities said the investigation would try to determine whether the target of the rocket attack was Aqaba or the Israeli resort of Eilat less than 10 kilometers (six miles) away.
In August 2005, three Katyusha rockets were fired in Aqaba, missing two U.S. warships docked in the port. One hit a warehouse, killing a Jordanian soldier, while another struck across the border in Israel.
That attack was claimed by a group linked to al-Qaeda.
Israeli media reported earlier on Thursday that a Katyusha rocket splashed into the Red Sea off Eilat and that another had exploded on the outskirts of Aqaba.
Israel's Channel 10 initially said the rockets were fired from Jordan, but later said it was possible they had been launched from Egypt's Sinai peninsula.
Not from Sinai
Egyptian security officials denied that any rockets had been fired from Sinai, a rugged territory that borders southern Israel.
The Sinai was the site of a wave of attacks on tourists between 2004 and 2006 that killed more than 100 people, and last week hundreds of Israelis rushed home from there after an Israeli security alert.
The travel warning concerned an alleged plot to kidnap Israeli tourists.
An Israeli military spokeswoman said Thursday's incident was under investigation.
"This morning explosions and flashes of light were reported near the city of Eilat," she said.
"The homefront command and the Israeli police searched the city following the reports but no evidence indicating a security-related incident was found.
"A few hours following the incident it was reported that the remains of a Katyusha rocket were discovered near the city of Aqaba, Jordan. The (Israeli military) is currently investigating the source of the launch," she said.
The spokeswoman declined to give the source of the reports.
The Jordanian plant hit by the rocket lies on the northern outskirts of Aqaba, which belongs to a special economic zone established by the Jordanian city's authorities in 2001.
Aqaba and Eilat are the neighboring Red Sea ports of Jordan and Israel, which signed a peace agreement in October 1994 after decades of strained ties and conflict.