UNITED NATIONS (REUTERS) - The UN Security Council is urging countries to stop the payment of kidnap ransoms to extremist groups like Al-Qaeda, which have earned hundreds of millions of dollars from such crimes.

No new legal obligations were created by the British-drafted resolution - unanimously adopted by the 15-member council - as states are already required not to pay kidnap ransoms under an anti-terrorism resolution adopted in 2001.

"We estimate that in the last three and a half years, Al-Qaeda-affiliated and other Islamist extremist groups have collected at least US$105 million (S$134 million)," British UN Ambassador Mark Lyall Grant told reporters.

"It is therefore imperative that we take steps to ensure that kidnap for ransom is no longer perceived as a lucrative business model and that we eliminate it as a source of terrorist financing," he said. "We need to break that cycle."

The United States has estimated militant groups have received US$120 million over the past decade, including ransoms paid to Al-Qaeda in the Islamic Maghreb. The US and Britain do not pay ransoms, but some European governments do.

The resolution said member nations should "prevent terrorists from benefiting directly or indirectly from ransom payments or from political concessions and to secure the safe release of hostages". It also urges countries to encourage the private sector to follow relevant guidelines and good practices for preventing and responding to kidnappings by extremist groups.

The council noted that ransom payment "incentivises future incidents of kidnapping for ransom".

French President Francois Hollande has said Paris ended a policy of paying ransoms for hostages, but suspicion that it still does so - despite official denials - has been a source of tension with the United States. Last year, France brushed off an allegation by a former US diplomat that it paid a US$17 million ransom in vain for the release of three hostages abducted in 2010 from Niger.

A confidential Nigerian government report seen by Reuters showed that Nigerian Islamist sect Boko Haram was paid an equivalent of around US$3.15 million by French and Cameroonian negotiators before freeing seven French hostages last April.