New Jersey has sued the operator of an immigration detention centre that has become a flashpoint over allegations of inhumane conditions for detainees.

The lawsuit demands that the facility's owner, GEO Group, a private contractor, allow state health inspectors more access to the facility in the city of Newark, alleging "unsanitary food and drink preparation and storage".

The New Jersey health department also received a report of "potentially inadequate Tuberculosis infection control practices", according to the legal action.

The Department of Homeland Security (DHS) said health inspectors had already been granted access to the facility, and the lawsuit was "frivolous".

"ICE is committed to transparency, and Delaney Hall complies with all required state and local laws," the DHS statement said.

The agency also said that four representatives of the New Jersey State Health Department had been allowed into the facility on 28 May and they "inspected the foodservice department".

But New Jersey argues their access did not go far enough.

The state attorney general's lawsuit alleges that GEO Group turned away inspectors on 27 May, citing a high number of congressional visitors.

Access granted the following day to health department inspectors was "severely limited", the lawsuit alleges.

The legal action says the officials were denied access to Delaney Hall's medical unit that day.

"If the GEO Group - with a $1 billion government contract - has nothing to hide and the conditions inside Delaney Hall are as safe and as sanitary as this private corporation and the Trump Administration claim, then there is no legitimate reason why my health inspectors are being kept from full access throughout the building," New Jersey Governor Mikie Sherrill, a Democrat, said in a statement.

DHS and the GEO Group did not immediately respond to a request for comment.

Immigration advocates says some Delaney Hall detainees launched a hunger strike on 22 May in protest at conditions inside the facility.

DHS has denied there is a hunger strike.

Appearing at a cabinet meeting with President Donald Trump last week, DHS Secretary Markwayne Mullin said: "There was only a handful of individuals that was refusing to eat, because they want their ethnic group - or their ethnic right food.

"The fact is, we're giving them the calories they want. This isn't Holiday Inn."

The street outside Delaney Hall has become a focal point for sometimes violent protests by activists opposed to the Trump administration's immigration policies.

Senator Andy Kim, a New Jersey Democrat, said he was hit with pepper spray during one protest when he visited the facility on 25 May.

Over the weekend, Governor Sherrill rebuked some "masked individuals" for "aggressive and dangerous actions" against local police.

Newark has imposed an overnight curfew around the facility. On Monday night, protesters rallied in a designated area before the deadline took effect.

As curfew fell, Newark police officers escorted the demonstrators from the area and no arrests were reported.

Newark Mayor Ras Baraka, a Democrat, meanwhile called for the immediate closure of Delaney Hall as he announced a legal strategy to shut down the centre.

"This is a dispute about human lives, about people and the way they're being treated," Baraka told a press conference on Tuesday.

The city of Newark would continue to oversee police presence around the facility, the mayor added.

He was arrested last year after allegedly trying to force his way into the facility and he was charged with trespassing.

Delaney Hall is the latest immigration detention centre to become a flashpoint, following protests at the Dilley Detention Centre in Texas and the 26 Federal Plaza court in New York.