Police arrested two more people and were on Thursday (24 May) searching a new site in Manchester suspected of links to the bombing that killed 22 people at a pop concert. Greater Manchester Police say two men were arrested in the Withington area in the south of the city.
The arrests come as British authorities complained bitterly about investigation leaks by US officials.
Prime Minister Theresa May is expected to raise the issue of the leaks with President Donald Trump in Brussels later.
British officials are particularly angry that photos detailing evidence about the bomb used in the attack were published in the New York Times.
Greater Manchester Police released a statement condemning the leaks on behalf of the National Counter-Terrorism Policing units that suggested a severe rupture in trust between Britain and the United States, who have traditionally shared intelligence at the highest levels.
"When the trust is breached it undermines these relationships, and undermines our investigations and the confidence of victims, witnesses and their family," the group said.
"This damage is even greater when it involves unauthorized disclosure of potential evidence in the middle of a major counter terrorism investigation."
Police and security services are also upset that the name of bomber Salman Abedi was leaked by U.S. officials and published while police in Britain were withholding the name for what they said were reasons of operational security.
Home Secretary Amber Rudd complained the leaks could cost police "the element of surprise" in their bid to prevent future attacks.
Police are rushing to uncover the network thought to have helped Abedi in the attack.
Eight men have now been detained in connection with Monday's attack. A woman was arrested late Wednesday but was later released without charge.
Officers also raided a property in the Moss Side area of the city early Thursday and carried out a controlled explosion.
With Britain's terrorism threat level at "critical," meaning a new attack may be imminent, police are working around the clock to try to deter another atrocity.
Abedi died in Monday's blast at an Ariana Grande concert.