An Egyptian man charged with tossing petrol bombs at a pro-Israeli rally in Colorado, injuring a dozen people, spent a year planning his attack.

Mohamed Sabry Soliman, 45, has told investigators he wanted to “kill all Zionist people” but had delayed committing the attack in the city of Boulder until after his daughter had graduated from high school.

He also used petrol bombs instead of a gun because his status as a non-US citizen barred him from buying firearms.

The claims are detailed in state and federal court documents charging Soliman with attempted murder, assault and a federal hate crime.

Soliman appeared briefly in court on Monday (local time) via a video feed from the Boulder County Jail. He faces 16 counts of attempted murder in the first degree – and could be sentenced to 384 years in state prison if convicted on all of them, Boulder County District Attorney Michael Dougherty said.

Police and FBI affidavits quoted Soliman as saying he learned to shoot a gun in a class he took hoping to get a concealed-carry permit, but ended up using petrol bombs because of his immigration status.

He said he learned how to make the fire bombs from YouTube.

US Immigration and Customs Enforcement acting director Todd Lyons said Soliman had overstayed a tourist visa and had an expired work permit.

Trump administration officials immediately seized on Sunday’s violence as an example of why they are cracking down on illegal immigration.

A police affidavit filed in support of Soliman’s arrest warrant said he was born in Egypt, and lived in Kuwait for 17 years. Three years ago, he moved to Colorado Springs, about 60 kilometres south of Boulder, where he lived with his wife and five children.

“In light of yesterday’s horrific attack, all terrorists, their family members, and terrorist sympathisers here on a visa should know that under the Trump administration we will find you, revoke your visa, and deport you,” US Secretary of State Marco Rubio said on X.

According to the Boulder police affidavit, Soliman had planned his attack for a year.

It unfolded on the Pearl Street Mall, a popular pedestrian shopping district near the University of Colorado.

The victims were involved in a walk to draw attention to hostages seized in Hamas’ 2023 attack on Israel.

Four additional victims were identified on Monday, bringing the number of injured to 12.

“There were 16 unused Molotov cocktails that were recovered by law enforcement in the hours after the incident took place,” Dougherty said.

Investigators said they also found a backpack weed sprayer filled with petrol.

The attack was the latest act of violence aimed at Jewish Americans linked to outrage over Israel’s escalating military offensive in Gaza. It followed the fatal shooting of two Israel Embassy aides that took place outside Washington’s Capital Jewish Museum last month.

Authorities said they found 16 petrol-filled bombs near where Soliman was detained.

The federal affidavit references a video posted on social media during the attack showing Soliman “shirtless, pacing back and forth while holding what appear to be Molotov cocktails”.

A Department of Homeland Security spokesperson previously said Soliman had entered the US in 2022 and filed for asylum the following month.

“The suspect, Mohamed Soliman, is illegally in our country,” the spokesperson said.

“There are millions of individuals like this that we are attempting to locate from the past administration that weren’t properly screened that were allowed in,” Lyons said.

“I will tell you that’s a huge effort for ICE right now.”

US President Donald Trump said in a social media post that such attacks would not be tolerated.

“This is yet another example of why we must keep our Borders SECURE, and deport Illegal, Anti-American Radicals from our Homeland,” he said.

-with AAP