LONDON - Libya's new government has discovered an arsenal of chemical weapons whose existence Muammer Gaddafi had not declared to the outside world, David Cameron, Britain's prime minister, said late on Monday. The development could raise serious questions about the extent to which the late Libyan leader surrendered his weapons of mass destruction in 2003. High quality global journalism requires investment. Please share this article with others using the link below, do not cut & paste the article. Mr Cameron said in a speech in London that Libya's new leaders had revealed the existence of the undeclared stocks in recent days. His announcement was confirmed by the Organisation for the Prohibition of Chemical Weapons (OPCW), the international regulatory agency. At the start of the Libyan conflict earlier this year, western leaders knew that Tripoli had already destroyed 55 per cent of its declared stockpile of sulphur mustard chemicals and 40 per cent of its declared stock of precursor chemicals. Libya had also destroyed its arsenal of more than 3,500 unfilled aerial bombs shortly after joining the international chemical weapons convention in 2004. However, Libya's new leaders have now discovered two sites where chemical weapons have been stockpiled and whose existence was never declared to the OPCW. “Although Gaddafi agreed to declare and dismantle all his weapons of mass destruction, and although we made real progress diminishing the threat he posed, in the last few days we have learnt that the new Libyan authorities have found chemical weapons that were kept hidden from the world,” said Mr Cameron. A western official aware of the details of the discovery told the Financial Times: “There are violations of the international weapons convention and there are serious violations. This is not a minor infraction. This looks like deliberate obfuscation.” A British Foreign Office official said: “Clearly, this is a serious matter. The fact that these stocks were kept hidden and undeclared is a very serious omission that says a lot about the wider character of the [former] regime.” Michael Luhan, head of public affairs at the OPCW, confirmed that the organisation was looking into the statement by the country's new leaders. “The Libyan authorities have provided informal notification to us that these two sites have been uncovered and a general itemising of their contents,” he said. Mr Luhan said the OPCW was now looking to get a formal and detailed declaration of the contents of the site and would then dispatch inspectors to examine it in the next few weeks. But he said the OPCW was “not doubting the authenticity of the find”. One issue the regulator will need to look at is whether the chemical weapons stocks were primed and potentially deployable at short notice. The OPCW has given no indication of this, but has suggested that the stocks have not been discovered close to population centres. If the organisation goes on to confirm a violation of the international convention, this could partly undermine claims made by London in 2003 that it was worth doing business with Gaddafi in order to secure his abandonment of terrorist goals.