The public inquiry into the Grenfell Tower fire disaster may take years to conclude and may never establish the truth of what happened, critics have warned.

Theresa May announced on Thursday she was ordering a judge-led inquiry to ensure the events at the 24-storey block were "properly investigated".

While the move was welcomed by many MPs, there have been concerns it could drag on for years, like the inquiries into the Iraq War and the Bloody Sunday shootings, before it finally reports.

Solicitor Sophie Khan, who acted for some of those affected by the 2009 Lakanal House fire in which six people died, said it would achieve nothing for the families of the victims.

"I am concerned why she (Mrs May) has come out so quickly to say public inquiry," she told the Press Association.

"We have had these before.

"We have had the Iraq Inquiry, we have had the Northern Ireland inquiry, you don't get any results out of them.

"Nothing will happen because the Government will set the terms, the Government will decide when to hold it, the Government will decide what documents will be there, the Government will decide when the outcome will be."

She said by holding a public inquiry rather than a coroner's inquest, the families were being excluded from participating in the proceedings.

"They are trying to curtail their rights.

"By saying they will have a public inquiry they will cut them out totally of the investigation process," she said.

"The best way would be inquests so the families can participate, can cross-examine the witnesses, make submissions, put questions to the coroner, and for the coroner to lead it rather than the Government."

Communities Secretary Sajid Javid insisted Mrs May had been right to call an inquiry as the best way of establishing the truth.

"I think that it is absolutely right that it is independently looked at by a judge-led inquiry," he told the BBC Radio 4 Today programme.

"That inquiry will look at all these issues, decisions by this Government, former governments, by local authorities.

"That is the way it should be done, independently."

He said the Government would not wait for its findings before taking action to address the immediate concerns raised by the fire and would respond to any recommendations from the fire inspectors' report.

"Once we have the investigative report, I'm not talking about in weeks or months, the early conclusions, we need to act immediately," he said.

"We need to do whatever it takes to make people who live in those properties safe."

Barrister Nicholas Griffin QC, who has worked on a number of public inquiries, said the success of the inquiry would depend on getting the terms of reference right.

"The terms of reference are key to the success of the inquiry because if you have them as too focused you may not have the depth that you need," he said.

"If they are too broad it may go on for much too much time and cost a lot of money.

"You have got to get that balance."

He said that while, in theory, the inquiry could proceed in parallel with any criminal investigation by the police, in practice there could be difficulties.

"In theory you can have the two things going on side-by-side," he said.

"In practice there may be difficulties if you have an inquiry that is looking into exactly the same thing a criminal investigation is looking into because the inquiry is not going to want to do anything that is going to prejudice that criminal investigation."