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LONDON — The parents of a extremely sick baby stormed out of court during a hearing Thursday to decide whether their son can receive experimental treatment they believe could save his life.

The plight of Charlie Gard has garnered worldwide attention and been highlighted by President Donald Trump and Pope Francis.

Parents Chris Gard and Connie Yates left the court after reacting to comments made by Judge Nicholas Francis.

Charlie's father said: "I thought this was supposed to be independent," as the couple left the courtroom two hours into the hearing, NBC News' U.K. partner, ITV News, reported.

As proceedings began, Francis said "it seems extremely unlikely that we'll reach the stage today that will make a final determination either way."

The parents later returned about an hour later after a break in court action.

Francis said on Monday that he would allow new evidence to be presented after a series of earlier rulings supported doctors' decision to remove the child’s life support.

Speaking as Thursday's hearing began, Francis said the child’s “welfare is the paramount concern of all of us although we may approach it in different ways.

As the parents arrived at court, their spokesman Alasdair Seton-Marsden read out a statement on their behalf.

“We are continuing to spend every moment working around the clock to save our dear baby Charlie,” Seton-Marsden said.

“We’ve been requesting this specialized treatment since November and never asked the hospital, the courts or anyone for anything except for the permission to go. We have raised over £1.3 million ($1.7 million) and had invitations from specialized doctors in the U.S. and Italy.

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“We hope that the courts and the judge will finally rule in favor of us seeking treatment elsewhere. We love him more than life itself. If he is still fighting then we are still fighting,” Seton-Marsden added.

Seton-Marsden had stirred controversy Wednesday when he appeared on FOX News saying that Baby Charlie was essentially being held "captive."

He also said the parents' situation would be in a very different if they were rich and had gone to a private hospital rather than one on Britain's publicly funded NHS.

Related: Trump Tweets Support For Terminally Ill Baby

Baby Charlie suffers from a rare genetic condition, an inherited mitochondrial disease generally referred to as MDDS, or mitochondrial DNA depletion syndrome. As a result, he is unable to move his arms or legs or breathe unaided.

He has been treated at the Great Ormond Street Hospital (GOSH) in London.

Baby Charlie Gard with his parents, Connie Yates and Chris Gard. Go Fund Me

The child’s parents have fought to raise $1.8 million to pay for experimental treatment that they believe could help.

But British and European courts have so far sided with the hospital's decision that the child’s life support should end, saying therapy would not help and would cause more suffering.

Last week, however, GOSH said it had applied for a new court hearing "in light of claims of new evidence relating to potential treatment for his condition."

The evidence came from researchers at the Vatican's children's hospital and another facility outside of Britain, the Associated Press reported.

If we can help little #CharlieGard, as per our friends in the U.K. and the Pope, we would be delighted to do so. — Donald J. Trump (@realDonaldTrump) July 3, 2017

Both President Donald Trump and Pope Francis have spoken out about the child’s plight.

Trump tweeted last week that “If we can help little #CharlieGard, as per our friends in the U.K. and the Pope, we would be delighted to do so.”

And the Vatican has said the pope is following the case "with affection and emotion" and "expresses his own closeness to his parents.”

On Monday, the child’s mother said that the input from Trump and the Pope had “saved [Charlie’s] life so far” by turning his plight “into an international issue.”

People gather in support of continued medical treatment for critically-ill 11-month old Charlie Gard due to be taken off life support, in London on Thursday. BEN STANSALL / AFP - Getty Images

A White House official said last week that members of the Trump administration, but not the president, had spoken to the parents in calls facilitated by the British government.

The official also said the president wants to be helpful without placing undue pressure on the family.

Charlie’s parents are also being supported by the controversial Rev. Patrick Mahoney, pastor at the Church on the Hill in Washington D.C. who has come to London to drum up support to keep Charlie alive.

On Sunday, Republican congressmen Brad Wenstrup and Trent Franks called for the child to be given U.S. residency so he can undergo treatment in the U.S..

Also on Sunday, Yates and Gard delivered to doctors at GOSH a petition organized by the Washington D.C. based anti-abortion law firm and advocacy group Americans United for Life.

Seton-Marsden said Thursday that seven petitions relating to their son’s case had now received 800,000 signatures and they hoped to reach one million by the end of the day.