Metropolitan Police Commissioner Cressida Dick has denied that there was an intelligence failure leading up to last Saturday’s London Bridge attack.
Speaking to the BBC Asian Network, she said: “Every bit of information is taken seriously.”
One attacker had been the subject of a call to the anti-terror hotline and featured in a jihadi documentary, prompting criticism of police.
Ms Dick said the Met and intelligence services would review their actions.
Police defended their decision to downgrade an inquiry in 2015 into Khuram Butt, 27, of Barking, east London, who is believed to have been the attack’s ringleader.
One man called the anti-terror hotline and officers had also viewed the Channel 4 documentary, The Jihadis Next Door, but police said there was no evidence of an attack being planned.
She said: “At the present time I do not regard what I have seen as an intelligence failure, but everybody would expect us to look at what has happened and to ensure that both we learn everything that we can, and that we improve and improve and improve.”
Despite the demands on police after the attacks in Westminster, Manchester and at London Bridge, Ms Dick said morale among officers was high.
“What happened in the last 12 weeks with the attacks in London and Manchester and with the five plots which we have thwarted, which had murderous intent and we stopped them, has only given my officers, my staff, the Metropolitan Police, more resolve, more determination,” she said.
“I think it’s brought the country together, the terrorists want to divide us, and it’s brought the Met together. People are absolutely determined to do everything they can to stop such an attack in the future.”
After an election in which the parties clashed over police funding to fight terror, Ms Dick said that she and other anti-terror agencies would be reviewing what was needed in order to prevent further attacks.
“I’m not going to say that definitely means this number or that number more pounds or more people let alone more officers,” she said.
“I do anticipate that when we take a long hard look at how we are dealing with the spread of work that the Metropolitan Police has and this changing terrorist threat, we will be asking for more resources in the future.”
The commissioner was speaking after police had revealed new details of the 3 June terrorist attack in London, which killed eight people and injured 48.
The attackers had previously tried to hire a seven-and-a-half tonne lorry before using a rented van to ram pedestrians, police said.
After crashing the van, they used 12in (30cm) pink ceramic knives tied to their wrists to attack passers-by.
In the back of the van used in the attack, officers also found wine bottles filled with flammable liquid with rags tied to their necks, along with blow torches to light them.
A safe house in Barking, east London, discovered by police contained a copy of the Koran opened at a page describing martyrdom, equipment for making petrol bombs, and plastic bottles and duct tape for constructing fake suicide bomb vests.
Forensic evidence at the house suggested that the three attackers, who were shot and killed near Borough Market by police, acted alone.
Briefing reporters, Commander Dean Haydon said police had shown “incredible bravery” and praised the public response.
He said: “We have stories of people armed with chairs, bottles, anything they could get their hands on with a view to trying to prevent the attackers coming to pubs and bars but also scaring them off to prevent other people being attacked.”
By Saturday, there had been 20 arrests, 13 buildings searched and 282 witnesses from 19 countries had been questioned in the investigation.