Manchester Attack: PM May Says U.K. Terror Threat Level to Remain at Critical

Bomb threat at local college deemed false alarm, police report | UK to stop sharing intelligence with U.S.

Flowers, messages and candles are pictured alonside a t-shirt from Ariana Grande's Dangerous Woman tour in St Ann's Square in Manchester, northwest England on May 25, 2017, placed in tribute to the victims of the May 22 terror attack at the Manchester Arena.

British Prime Minister Theresa May said on Thursday the terror threat level in the U.K. will remain at critical, following a suicide bombing that killed 22 at an Ariana Grande concert on Monday.

The threat level was raised to critical, its highest level, on Tuesday, for the first time in 10 years.

"The threat level, as assessed by the independent joint terrorism analysis center, will remain at critical and the public should remain vigilant," May said following a meeting of the government's emergency response committee. 

Police are hunting for a possible bomb-maker after the 22-year-old attacker, British-born Salman Abedi, detonated a sophisticated device at a concert venue packed with children. In addition to the 22 people who died, 64 were injured.

A reported suspicious package in Manchester which British army bomb disposal experts investigated has been deemed safe, police said Thursday.

This photo obtained May 24, 2017 courtesy of The New York Times ( from British Law Enforcement, shows what the bomber in the Manchester terrorist attack appeared to have use to detonate a powerful explosive in a lightweight metal container concealed within a blue Karrimor backpack, according to preliminary information gathered by British authorities in Manchester, England.

>> Report: U.K. stops sharing information on Manchester attack with U.S. after intelligence leak <<

May also said on Thursday she would "make clear" to U.S. President Donald Trump that intelligence shared between the two countries must remain secure, the Press Association reported.

British ministers and security chiefs have been dismayed by leaks in the U.S. media which police fear could hinder a hunt for a possible bomb-maker still at large.  Local media said the U.K. government is "furious" over the leaks of details about the investigation into a blast which killed 22 at an Ariana Grande concert on Monday.