Shared intelligence must remain 'secure,' British Prime Minister Theresa May tells US President Donald Trump

US President Donald Trump (R) speaks with British Prime Minister Theresa May during a working dinner meeting at the NATO (North Atlantic Treaty Organization) summit at the NATO headquarters, in Brussels, on May 25, 2017. (Photo by AFP)

British Prime Minister Theresa May has reportedly brought up the issue of intelligence leaks from an investigation into the Manchester attack during a discussion with President Donald Trump.

According to a British government source, the UK premier raised the issue of the intelligence leaks with the US president while they were waiting for a group photograph to be taken at a NATO summit in Brussels on Thursday.

"She expressed the view that the intelligence sharing relationship we have with the U.S. is hugely important and valuable, but that the information that we share should be kept secure," the source said.

Earlier, while speaking in 10 Downing Street in central London ahead of her departure for the NATO meeting, May said, "I will make clear to President Trump that intelligence that is shared between our law enforcement agencies must remain secure."

Britain's Prime Minister Theresa May leaves 10 Downing Street in central London on May 25, 2017. (Photo by AFP)

British officials have expressed outrage over the US leaking of classified evidence tied to the Manchester attack and UK police have stopped sharing information on the suicide bombing with the US.

The New York Times on Wednesday released some of the initial evidence that British police had gathered from the scene of the bombing at the concert led by American singer Ariana Grande in Manchester Arena the day before.

The report included pictures of the remnants of a backpack and a battery that investigators believed were used by Salman Abedi, the alleged 22-year-old suspect, to carry and detonate an improvised explosive device (IED).

UK Home Secretary Amber Rudd on Wednesday described the leaks as "irritating."

Britain's Home Secretary Amber Rudd leaves 10 Downing Street following the weekly meeting of the cabinet in central London on April 25, 2017. (Photo by AFP)

"The British police have been very clear that they want to control the flow of information in order to protect operational integrity, the element of surprise," Rudd told BBC Radio.

"So it is irritating if it gets released from other sources and I have been very clear with our friends that that should not happen again."

At least 22 people lost their lives and dozens more wounded after Abedi allegedly detonated his explosives at a concert hall in Manchester on Monday.

British medical sources have raised the number of injuries to 119. Twenty of those with traumatic injuries are still in critical condition. Daesh terrorists have claimed responsibility for the attack. 

Trump vows to find and punish source of Manchester attack leaks

US President Donald Trump reacts as he arrives for the NATO summit at the NATO headquarters, in Brussels, on May 25, 2017. (Photo by AFP)

Meanwhile, Trump has finally responded to the leaks related to the Manchester attack investigation.

He said on Thursday the leaks are "deeply troubling" and has vowed "to get to the bottom of this".

He said he had ordered the Department of Justice to launch a full investigation into the issue. 

"The alleged leaks coming out of government agencies are deeply troubling,” Trump said in a statement, adding that he “will get to the bottom of this” because they “pose a grave threat to our national security.”