Metropolitan Police released a statement from Deputy Assistant Commissioner Neil Basu, a counterterrorism coordinator.
"This is a proportionate and sensible step which will provide extra reassurance and protection while the investigation progresses".
The police say he will be moved to a south London police station.
British media reported that the crude device, carried in a bucket and shoved into a shopping bag, had a timer, suggesting that some degree of bombmaking knowledge was employed. None of the injuries are thought to be life-threatening.
London police began a manhunt after an explosion Friday aboard a crowded London subway car in what police say is a terror-related attack.
Prime Minister Theresa May said after the attack that the country's Joint Terrorism Analysis Center decided to raise the country's threat level to critical, meaning that a further attack may be imminent.
Speaking on the campaign trail in Rotorua, Mr English said one New Zealander had been caught up on the attack, and had been taken to hospital, treated and discharged.
"The public should remain vigilant as our staff, officers and partners continue to work through this complex investigation", he said.
The claim of responsibility came as the UK's terror alert level was raised to critical, with military troops set to bolster police forces as they hunt the bomber.
US President Donald Trump denounced the attack on Twitter saying: "Another attack in London by a loser terrorist". Ambassador to London Antonio Lagdameo said they are continuously monitoring the situation.