Human rights campaigners warn, in the approach to Valentine's Day, that an international system of regulating the gem trade is being systematically bypassed. Millions of men, women and children are being killed, injured and made homeless as a result. According to a Global Witness and Amnesty International report released today, "conflict diamonds" from Liberia are being smuggled into neighbouring countries for export, and stones from strife-torn Ivory Coast are also finding their way on to the British and other European markets.

In Liberia, a bitter eight-year civil war, which has killed more than 200,000 people and displaced more than a million, has been fuelled by the illegal diamond trade. Diamonds from Ivory Coast are smuggled to Mali and sold on the international market to provide millions of dollars in revenue for rebel factions such as the Forces Nouvelles.

Amnesty International and Global Witness are calling on the public to protest against the international trade in conflict diamonds. Shoppers are being urged to ask sales staff at jewellers where their diamonds come from and whether the areas are conflict-free.

Under existing guidelines retailers should be able to provide a copy of their company policy on conflict diamonds and a written guarantee from suppliers about the origin of the stones.

"Despite some progress, we are still concerned that the UK diamond industry is falling short in combating the trade in conflict diamonds," said Tom Fyans, Amnesty International UK economic relations manager, who claimed that a recent survey revealed only 18 per cent of stores could provide any assurance.

Since 2003, following a big international campaign highlighting the consequences of the trade in conflict diamonds, an international certification scheme called the Kimberley Process has been in place, which means a certificate, guaranteeing diamonds as conflict-free, should accompany all shipments of rough diamonds to and from participating countries.

In addition all sectors of the diamond industry, including high-street retailers, agreed to a voluntary system of warranties to ensure diamonds continue to be tracked right up to the point of sale. "All the diamond producing countries, the traders and the retailers voluntarily agreed to provide guarantees to the point of sale so that consumers can walk into a high street shop and be sure they are getting a good, clean diamond," said Sarah Green, spokeswoman for Amnesty International, yesterday. " Unfortunately what was agreed has not been followed through. We know that a lot of conflict diamonds are creeping into the system and many retailers are not bothering to make warranties available.

"When we carried out a street-level survey only 18 per cent of stores could provide a copy of their conflict diamond policy and 22 per cent admitted they had no policy at all."

In the past warlords and rebel groups in countries including Angola, the Democratic Republic of Congo, Liberia and Sierra Leone have used billions of dollars of profits from the sale of diamonds from the mines they control to buy arms and fund devastating wars.

According to Amnesty International and the campaign group Global Witness, rough diamonds mined in rebel-held areas of Ivory Coast and Liberia are still being traded.

The illegal stones are smuggled out of conflict areas and into neighbouring countries where they are either sold on the black market or mixed in with legitimate Kimberley-certified diamonds and passed off as being sourced from elsewhere.

"Diamonds have provided funding for several brutal conflicts in Africa, resulting in the death and displacement of millions of people," says a report compiled by Global Witness into the continuing illegal trade. Four months ago a Global Witness investigation into the trade discovered that diamonds were being smuggled out of Ivory Coast by rebel agents to Mali and Guinea where they were sold to international traders.

Hundreds of labourers are being forced to work in diamond pits in three villages - Seguela, Bobi and Diarabala - in the north of the country to extract up to 300,000 carats a year worth more than $25m (£14m).

In addition Global Witness claims that international terrorist groups including al-Qa'ida have infiltrated diamond trading networks to raise funds for their cause and launder huge amounts of money.

Among the areas targeted by al-Qa'ida is believed to be the illegal operations in Liberia, which was used as a conduit for diamonds mined by the rebel group the RUF during the war in Sierra Leone which was responsible for the deaths of at least 50,000 people and the mutilation, rape, torture and abduction of thousands of others. So far more than 200,000 lives have been lost in Liberia as a result of the conflict there.

"Things have got a lot better since the Kimberley Process was set up in 2003 but there is still a lot that can be done," said Susie Sanders of Global Witness, who said that at one time it was estimated that one in six diamonds was a conflict diamond but now, with the stricter controls in place, that percentage is now very small.

"We want people to help put pressure on the retailers who, in turn, will put pressure on their suppliers to end once and for all the trade in conflict diamonds," said Ms Sanders.

"Diamonds may be expensive, but they shouldn't cost lives."

Ask before you buy

Every consumer can help ensure diamonds never again fund conflict by asking four simple questions. Before buying a diamond, shoppers should ask the sales person the following:

1. How can I be sure that none of your jewellery contains conflict diamonds?

2. Do you know where the diamonds you sell come from?

3. Can I see a copy of your company's policy on conflict diamonds?

4. Can you show me a written guarantee from your diamond suppliers stating that your diamonds are conflict-free?

"They should be only too pleased to help you," says a campaign guide from Amnesty International and Global Witness. "If they aren't, try somewhere else, and tell them why."