Manchester, UK: Britain raced on Thursday to track down a jihadist network suspected of orchestrating the Manchester concert attack, as a row escalated between London and Washington over leaked material from the probe.

As more children were named among the 22 victims of Monday’s massacre, the suicide bomber’s father and brother were arrested in Libya and British police arrested a seventh person in connection with the investigation.

But they were left ‘furious’ by repeated leaks of material shared with their US counterparts, which provides an awkward backdrop for Prime Minister Theresa May’s meeting with US President Donald Trump at the NATO summit in Brussels later Thursday.

In Manchester, northwest England, feelings were still raw following Abedi’s attack on a concert by US pop star Ariana Grande—especially so as the bomber was born in the city.

But Manchester United fans stood together in defiant mood as their team’s triumph in European football’s Europa League final brought some much-needed smiles to a city still in pain.

The club dedicated their trophy to those killed, while manager Jose Mourinho said they would gladly exchange it if it could bring their lives back.

According to photographs from the scene of Monday’s attack at the 21,000-capacity Manchester Arena, Abedi’s device appeared to be fairly sophisticated.

Images obtained by The New York Times newspaper showed a detonator that bomber Salman Abedi was said to have carried in his left hand, shrapnel including nuts and screws, and the shredded remains of a blue backpack.

Anger at US leaks

But after of the bomber’s identity and details of the probe were leaked, the intelligence-sharing relationship between close allies London and Washington was left rocking.

‘We are furious. This is completely unacceptable,’ a government ministry source said of the images ‘leaked from inside the US system’.

The National Counter Terrorism Policing body said the breach of trust caused great ‘damage’ and ‘undermines our investigations’.

University dropout Abedi, 22, grew up in a Libyan family that reportedly fled to Manchester to escape the now-fallen regime of Libyan dictator Moamer Kadhafi.

His father Ramadan and younger brother Hashem were detained in Libya, authorities there said.

A spokesman for the Deterrence Force, which acts as Libya’s Government of National Accord’s police, said the brother was aware of Abedi’s plan and the siblings were both members of the Islamic State jihadist group.

The attack was the latest in a series of deadly incidents across Europe claimed by IS that have coincided with an offensive on the group’s redoubts in Syria and Iraq carried out by US, British and other Western forces.

Hashem had been ‘under surveillance for a month and a half’ and ‘investigation teams supplied intelligence that he was planning a terrorist attack in the capital Tripoli’, the Deterrence Force said on its Facebook page.

A relative told AFP that Abedi had travelled to Manchester from Libya four days before the bombing.