LONDON — London police charged a suspect yesterday with conspiracy to murder and possession of explosives in the failed July 21 attacks — the first charges to be laid in Britain against any of the would-be bombers.

Yassin Hassan Omar, 24, is suspected of trying to bomb a subway train near Warren Street station July 21. The Metropolitan Police said he was charged with conspiring "with others unknown to murder passengers on the transport for London system."

The July 21 attacks came two weeks after suicide bombers killed 56 people on three subway trains and a bus.

Omar, who was arrested in the English city of Birmingham on July 27, faces three other charges: attempted murder; making or possessing an explosive substance with intent to endanger life or cause serious injury, and conspiracy to use explosives.

Two other suspects in the failed July 21 bombings were arrested in London on July 29. A fourth was arrested in Rome and is being held there on international terrorism charges.

In response to the bombings, Prime Minister Tony Blair announced tough measures to crack down on extremist Islamic clerics. The government defended the plans yesterday, as critics warned the measures could further alienate British Muslims.

Britain's chief legal official, Lord Chancellor Charles Falconer, said the deadly attacks in London on July 7 showed the government must act against people "who are encouraging young men who are becoming suicide bombers."

"A new balance needs to be struck. It needs to be a lawful balance, but it needs to be an effective balance," he told BBC radio.