The sanctuary city of Portland has announced it will issue a land use violation notice on Thursday to a local U.S. Immigration and Customs Enforcement (ICE) building, accusing it of repeatedly holding detainees longer than permitted and escalating a fight over a building that has already drawn months of protests, some of which have turned violent.

Officials said the notice will start a review of whether the Macadam Avenue facility is following the rules of its 2011 land use permit, which bars keeping people overnight or for more than 12 hours.

It follows a report by a local non-profit group accusing the facility of holding people for longer than permitted 25 times between Oct. 1 and July 27. The report by the Deportation Data Project was generated using ICE documents obtained through the Freedom of Information Act. 

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The city will also issue a second violation regarding boarded-up windows at the facility, which is not associated with the land use approval. ICE did not immediately respond to a Fox News Digital request for comment.

"U.S. Immigrations and Customs Enforcement made clear detention limitation commitments to our community, and we believe they broke those policies more than two dozen times," Portland Mayor Keith Wilson, a Democrat, said in a statement. "I am proud of our team for conducting a thorough, thoughtful investigation and referring the matter to the next steps in the land use violation process." 

Under land use permitting rules, a landowner or operator has 30 days after receiving a notice of violation to correct the issue. If substantial evidence of a violation exists, a fine can be issued. The city can also initiate a "reconsideration" of a land use approval by scheduling a hearing at least 60 days after the notice. 

The facility has become a major flashpoint for President Donald Trump’s immigration clampdown as left-wing protesters and agitators have descended on the facility several times.

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The building's exterior has been covered in anti-ICE graffiti while several violent clashes between agitators and federal agents have broken out several times since June, including in one incident where a large group of anti-ICE protesters tried to block law enforcement vehicles from entering and exiting the facility, forcing agents to deploy rubber bullets, tear gas and flash bangs to disperse the crowd.

Last month, anti-ICE protesters were captured on video rolling out a guillotine and clashing with police before law enforcement fired munitions to disperse the crowd.

In July, Portland's progressive-leaning city council said it was exploring ways to expel ICE from the detention facility.

Under Portland's sanctuary policy, city employees, including police officers, do not enforce federal immigration law. Oregon also has a sanctuary law that prohibits state and local law enforcement from participating in immigration enforcement without a warrant.

In the wake of violent Labor Day protests, Wilson doubled down on the city's commitment to sanctuary policies.

"You can rest assured we won’t be engaging with or working with ICE in any circumstances," he said. 

The building is leased and managed by the General Services Administration (GSA) for federal agencies tied to ICE. It includes a processing center where officers detain and interview people to determine their immigration status.

The Associated Press contributed to this report.