Under mounting pressure after a botched election and facing criticism for not meeting victims of a London tower block blaze sooner, British Prime Minister Theresa May visited the injured in hospital on Friday as the death toll rose to 30.

Opposition Labour leader Jeremy Corbyn, London mayor Sadiq Khan, Prince William and Queen Elizabeth, 91, have all visited residents from the 24-storey Grenfell Tower destroyed on Wednesday as many slept, and anger is growing in the community.

May has been criticised from within her own Conservative Party over her response and she pledged on Thursday to hold a public inquiry into the fire at the social housing block which was home to about 600 people. The toll is expected to rise.

May met victims privately at a central London hospital on Friday and had expressed her sorrow on television on Thursday after meeting emergency services personnel.

"She should have been there with the residents. You have to be prepared to receive people's emotions, and not be so frightened about people," former Conservative cabinet minister Michael Portillo told the BBC.

READ: Huge fire engulfs 27-floor London tower block

Khan wrote to May on Friday, saying residents felt increasingly enraged and frustrated by the slow response from the authorities.

"The local community feels their grief has been made worse by the lack of information about their missing family members and friends," he wrote. Residents in other blocks with the same exterior cladding as Grenfell Tower were concerned, he wrote.

"People are terrified that the same thing could happen to them," Khan wrote in the letter.

May's response has been contrasted with that of Corbyn, who hugged locals at the estate during his visit on Thursday, and the royals who met residents and volunteers on Friday.

TERRIBLE

"That's one of the most terrible things I have ever seen," Prince William said of the tower's blackened shell.

Some desperate residents pleaded to speak to the queen and her grandson about their plight and the fate of missing children as they left the site, with William promising he would return.

There has been growing fury on the low-rent estate where residents wanted answers on why the fire was able to spread so rapidly and why complaints about safety had been ignored.

However, Foreign Secretary Boris Johnson took to Facebook to attack Labour politicians for "political game playing", defending his record regarding the fire service as mayor of London between 2008-2016.

"Any attack on emergency services performance is outrageous politicking by Labour," he said.

London police said an investigation, led by a detective from its homicide and major crime unit, would examine whether criminal offences had been committed although they said there was nothing to suggest the fire was started deliberately.

Commander Stuart Cundy said they had been able to remove the remains of only 12 victims from the building.

"Sadly, it is expected that the total will rise and it is not expected that any survivors will be found," he said. Police have said it could take months to search the building and some victims might never be identified.

Locals were expected to stage a march in Kensington, where social housing tenants live cheek by jowl with billionaires in one of Europe's richest districts, from 3 p.m. (1400 GMT) while a rally to demand justice for the victims was due to start in the government district of Westminster at 1700 GMT.

While the disaster has prompted an outpouring of generosity, there was also anger at politicians as the charred tower was cast as a deadly symbol of a divided society.

May had also drawn criticism during the election campaign for seeming wooden and reluctant to engage in open debate with political rivals and voters, but local government minister Sajid Javid, responsible for housing policy, defended her on Friday.

"What she wanted to do was to speak to the people working on the ground on the recovery operation, the rescue operation to make sure that they've got everything they want and see how she could help," he told Sky news.

May failed to win an outright majority in the June snap election and is now battling to strike a deal with Northern Ireland's Democratic Unionist Party to support her government.