FBI Director Kash Patel has said a US judge has been arrested for obstructing an immigration operation, escalating tensions between Donald Trump's administration and the country’s judiciary.

"The FBI arrested Judge Hannah Dugan out of Milwaukee, Wisconsin on charges of obstruction — after evidence of Judge Dugan obstructing an immigration arrest operation last week," Patel posted on his X account on Friday.

"We believe Judge Dugan intentionally misdirected federal agents away from the subject to be arrested in her courthouse, Eduardo Flores Ruiz, allowing the subject — an illegal alien — to evade arrest."

Minutes later the Trump-appointed FBI director deleted his post, and Dugan's status remained unclear.

Dugan was arrested early on Friday at the courthouse, a law enforcement official confirmed to ABC News.

"Thankfully our agents chased down the perp on foot [Flores Ruiz] and he's been in custody since, but the Judge's obstruction created increased danger to the public," Patel added.