Authorities in Jordan have disrupted a major terrorist plot by al-Qaeda-linked operatives to launch near-simultaneous attacks on multiple civilian and government targets, reportedly including the U.S. Embassy in the capital, Amman, Western and Middle Eastern officials said Sunday.

The Jordanian government issued a statement describing the plot and saying that 11 people with connections to al-Qaeda’s affiliate in Iraq have been arrested.

The foiled attack, described as the most serious plot uncovered in Jordan since at least 2005, was viewed with particular alarm by intelligence agencies because of its sophisticated design and the planned use of munitions intended for the Syrian conflict — a new sign that Syria’s troubles could be spilling over into neighboring countries, the officials said. 

The alleged plotters are Jordanian nationals. The officials said the group had amassed a stockpile of explosives and weapons from Syrian battlefields and devised a plan to use military-style tactics in a wave of attacks across Amman. 

The scheme called for multiple strikes on shopping centers and cafes as a diversionary tactic to draw the attention of police and security officials, allowing other operatives to launch attacks against the main targets, which included government buildings and embassies.

Pictures of Abd Alfattah So'ud Abd Alfattah Dardas, Tareq Ali Mahmoud Al Shara'a, Ja'afar So'ud Abd Alfattah Dardas and Ayman Ahmad Salam Abu Sa'eleek, four of 11 suspects detained by security forces, are seen in this handout released by Jordan's official Petra news agency on October 21, 2012. Jordan foiled a major plot by an al Qaeda-linked cell to destabilise the country's security by bombing shopping centers and assassinating Western diplomats, state television said on Sunday. (Handout/Reuters)

A Western official briefed on details of the plot confirmed that the heavily fortified U.S. Embassy in Amman was among the targets. Like others interviewed for this report, the official spoke on the condition of anonymity because the investigation is still unfolding.

The Jordanian government’s statement said its intelligence service had broken up a cell that had been planning the attacks since June, arresting 11 people described as “supporters” of al-Qaeda in Iraq. The group had intended to use explosives and mortar rounds acquired from Syria, as well as machine guns, car bombs and militia-style guerrilla tactics, to ensure “the highest death toll,” according to the statement. 

The suspects had traveled to Syria multiple times and brought weapons with them, government officials said. They were arrested less than a week after Jordanian officials captured three Jordanians as they attempted to cross illegally into Syria, allegedly to join radical Islamist militias fighting Syrian loyalists there.

In a news conference late Sunday in Amman, Jordanian government spokesman Samih Maaytah said that the plot was “not related to the Syrian crisis” and that “Jordan will not change its approach” to the conflict in response to the discovery.

The timing of the plot was viewed as curious. Jordan has increasingly allied itself with forces seeking the overthrow of Bashar al-Assad, the Syrian autocrat opposed by rebels as well as a growing cadre of foreign Islamist militants inside Syria. Jordan hosts hundreds of thousands of Syrian refugees within its borders and has helped deliver humanitarian aid to rebel-held cities. 

But intelligence gleaned from surveillance of the cell suggests that the plotters intended to destabilize Jordan’s pro-Western government with massive blows against government institutions and tourism-dependent economy, the officials said. 

“This was a serious plan, with a great potential for loss of life,” said a former Western intelligence official briefed on the details. For Jordan, beset by economic problems and deepening political unrest, he said, “this may not have been a tipping point, but it could have been a very hard blow.” 

The former intelligence official said the plotters had access to large amounts of explosives from Syria and intended to use them to construct massive bombs. 

“Weapons are everywhere right now, flowing from Iraq into Syria, and back and forth into Lebanon,” the former official said. “The longer the conflict goes on, the worse it gets.” 

Also Sunday, a Jordanian soldier was killed in a clash between government security forces and a band of 16 armed militants seeking to cross illegally into Syria, government officials said. Four of the gunmen also were killed in the 20-minute firefight, the first to claim the life of a Jordanian officer since the Syrian uprising began.

The State Department had no immediate comment on the plot and declined to confirm or deny that the U.S. Embassy in Amman had been on the target list. 

The last major terrorist strike in Jordan occurred in 2005, when al-Qaeda militants launched simultaneous attacks against three Amman hotels, killing 60 people and wounding 115. 

Luck reported from Amman. Joel Greenberg in Jerusalem contributed to this report.