What is al-Qaeda?

Brit Richard Reid, who tried to blow up a plane, was a supporter of Al Qaeda

Al-Qaeda has been accused of being behind a series of attacks and bombings since its formation in the late 1980s.

Because of this, it is classed as a terrorist organisation by the UK government.

Members are followers of Islam but they have very extreme beliefs that are different from those of many Muslims.

They believe they are fighting a holy war (jihad) against enemies of their religion.

Al-Qaeda hopes its attacks will make Western countries treat Muslims differently in areas like the Middle East, the Balkans and Chechnya .

People have joined the group from many countries including Britain.

They operate internationally but are thought to be strongest in Arab countries.