The Into You hitmaker had just finished performing to 21,000 fans at Manchester Arena on Monday evening (local time) when there was an explosion in the foyer of the venue, killing 22 people. A 23-year-old man was arrested in the south of the city yesterday.
The British government says a national minute of silence will be observed on Thursday to remember those who died or were affected by Monday's bombing at Manchester Arena.
USA intelligence officials also prematurely leaked information about the suspected bomber on Tuesday, which led to the publication of Salman Abedi's name, as well the fact that the attack was a suicide bomb.
Officials say soldiers will be deployed to places like Buckingham Palace, 10 Downing Street and Parliament.
France's interior minister Gerard Collomb told French television that both British and French intelligence services had information that the attacker had been in Syria.
The calls are thought to have been made five years ago after Abedi left school, the community worker added. So, the question becomes: "Is there a person who executed the attack, and, in addition, at least one bomb maker?" The anti-terrorism force said the father had not been charged, but was taken in for questioning.
Hashem Abedi's arrest - a day after older brother Ismail was held - came as the men's father was also arrested in the Libyan capital. Before his arrest, he told news outlets that his son was innocent.
Ms Rudd confirmed Abedi had recently returned from a visit to Libya, and said the nature of the attack suggested he may have had support. He denied ties to any militant groups or suggestions of extremism.
Prime Minister Theresa May is expected to raise the issue of the leaks with President Donald Trump in Brussels later.
For a second night, a throng of people filled a Manchester square for a vigil for the victims. People lifted their hands in the air during a moment of silence.