It is a victory for victims' families, who want to know whether the bombings could have been prevented if the security services had followed up on leads pointing to the unfolding plot.

"The scope of the inquest into the 52 deaths will include the alleged intelligence failings and the immediate aftermath of the bombings," Judge Heather Hallett said in a ruling handed down at the High Court in London.

Intelligence agencies had argued that such a wide-ranging inquiry could compromise national security.

Hallett said the victims' families did not wish to endanger national security, but "want to know in essence the answer to two simple questions: Why were (the bombers) not put under surveillance? Had they been, might the London bombings have been prevented?" As well as events leading up to the bombings on July 7, 2005, the inquest will look at the emergency operation that followed. Some families want to know whether their loved ones would have survived had there been a quicker response.

Clifford Tibber, a lawyer for some of the survivors and victims' families, said the families felt "hope, expectation, relief" — but also disappointment that the government had rejected calls for a wide-ranging public inquiry into the attacks.

In Britain, inquests must be held any time someone dies unexpectedly, violently or of unknown causes.

Hallett said inquest hearings would start in October. She said she would hear the inquests without a jury, because of the sensitive intelligence material involved.

The judge also said inquests into the deaths of the four suicide bombers would be held separately from those of their victims.

She said some relatives had expressed "understandable and very public anxiety" at the idea of the killers' inquests taking place at the same time.

The bombings were carried out by British Islamists inspired by Al-Qaeda on three subway trains and a bus in the deadliest attack in Britain's capital since World War II.

Security officials have acknowledged that agents had the bombings' ringleader, Mohammed Sidique Khan, under surveillance more than a year before the attacks. He was followed and photographed by agents tracking another foiled plot, and domestic intelligence agency MI5 eventually decided he was not a priority target.