THE Red Cross, the Red Crescent and, most recently, the Red Crystal have been adopted as universal symbols of humanitarian aid.

• Red Cross

In 1864, this emblem - the colours of the Swiss flag in reverse - was adopted at an international diplomatic conference in Geneva.

It confers legal protection on army medical services, aid workers and war victims.

• Red Crescent

The Red Cross emblem has no religious intent.

But most Muslim countries - reminded of the Crusaders' cross from centuries earlier - refused to use it. During the 1876-1878 war between Russia and Turkey, the Ottoman empire declared it would use a red crescent.

In 1929, the Red Crescent was recognised by a diplomatic conference.

• Red Crystal

Following objections by some countries over the religious or political associations of the two earlier symbols, a diplomatic conference recognised the Red Crystal as a third emblem in December 2005.