Visiting South African cricketers "are uneasy" following Monday's suicide bomb attack on a pop concert in Manchester but abandoning their tour of England is not under consideration, the team's manager has said.

Britain has increased its security threat level to "critical" from "severe" following the attack that killed 22 people at an Ariana Grande concert at the Manchester Arena.

South Africa begin their three-month tour of England with a one-day international against the hosts at Leeds on Wednesday and team manager Mohammed Moosajee admitted the players were concerned.

"As you can understand we have some genuine concerns, the players are uneasy... there was a lot of chatter at the breakfast table," Moosajee told reporters at the Headingley ground.

"I am happy to say we've had constant communications from the ECB (England and Wales Cricket Board) and their security manager.

"There have been guarantees put in place that security arrangements will be supplemented, starting today. We're told there will be more visible police at the stadium, at practice sessions as well as the hotels we will reside at."

"The hotel we will stay at when we are in Manchester for the last Test match is walking distance away from where the events unfolded so there have been some genuine concerns..." Moosaji said.

"I think the process has started to make sure the players are reassured that arrangements are being made to try and keep them safe.

"As things stand, there's no mention of us even thinking of abandoning the tour. If the intelligence information tells us something else we would obviously have to reconsider."

The International Cricket Council (ICC) issued a statement on Tuesday saying it would review security of both the Champions Trophy and the month-long women's World Cup, also in England and Wales, beginning on June 24.

South Africa will also play two other one-day internationals following Wednesday's contest and three Twenty20 matches against the hosts as part of the tour.