GENEVA (AFP) - Thirty-one countries still hold stockpiles of cluster munitions despite signing a treaty to ban them, according to a report by anti-arms lobby groups published on Friday. Britain, Germany and the Netherlands hold the largest stocks, said the report by Human Rights Watch and Landmine Action. Britain has 38.7 million submunitions which are used in cluster bombs, Germany holds 33 million and the Netherlands has 26 million, the report said. The three count among 96 countries that have inked the Convention on Cluster Munitions since it opened for signing last December. Seven countries have since ratified the treaty, which needs 30 ratifications to come into force. Steve Goose, arms division director at Human Rights Watch, highlighted the changes in countries attitudes towards cluster munitions and said he expected the necessary ratifications this year. Were confident that we will get 30 ratifications during 2009... there are six or seven lined up now that are likely to come on board within the next month or so, he said, citing Spain, Germany and Japan as examples. But while the signatory states have committed to destroying the stockpiles, other countries that hold significant stockpiles have not, according to campaign groups. According to the report, the total global stockpile of submunitions contained in the cluster bombs likely number into the billions. The biggest volume of 730 million submunitions is held by the United States, which has not joined the treaty and is therefore not obliged to eliminate its stock. Goose told journalists in Geneva however that there was some progress on the issue from the United States. Since March, Washington has halted the export of cluster munitions. We are optimistic that the United States is going to review its policy on cluster munitions with the objective of being able to join this convention, said Goose. The fact that we already have an export ban in place... we think thats a strong indicator that theres acceptance on the part of the government and even the US military that this weapon has to be dealt with. Cluster munitions spread bomblets over a wide area from a single shell or bomb. The bomblets often do not explode on impact, but can do so later at the slightest touch. Therefore, they are just as deadly after a conflict as during. Seventeen countries including the United States, China and Russia are still producing cluster munitions this year. In 2009, it appears that cluster munitions are being produced to some degree in 17 states, said the report. Cluster munitions continue to be publicly listed as available products on the international arms market and continue to be displayed at some arms fairs, it added.