LONDON (Reuters) - The world's top drugmakers have improved access to medicines in developing countries, according to a report on Monday, but their good work is undermined by a sorry record of unethical behavior. The Access to Medicines Index, which ranks the 20 leading pharmaceutical companies every two years on how well they get treatments to the poor, said the industry's progress had been "uneven". Eighteen of the firms monitored were the subject of settlements or fines for corrupt behavior, unethical marketing or breaches of competition law in the last two years. "Commitment to ethical behavior does not correlate with performance," the report said, adding that companies were still reluctant to disclose details of drug patents. The independently compiled index, which had a skeptical reception from drug manufacturers when it started in 2008, is now widely tracked by drugmakers and investors, who see it as a proxy for companies' long-term success in emerging markets. The contradictory advances and the problems facing the industry are evident at GlaxoSmithKline, which retained its long-standing top spot in the index, while simultaneously featuring in a major bribery scandal in China. "Corruption is terrible, but it also takes attention away from the fact that these companies are doing quite a lot of good stuff," said Jayasree Iyer, research head at the Access to Medicine Foundation, based in the Netherlands. Denmark's Novo Nordisk moved up to the No. 2 spot, reflecting its coordinated approach to providing diabetes care at an affordable price in poorer countries. Sanofi and Pfizer were the biggest fallers down the rankings, while Japanese drugmakers came bottom, as in previous assessments. As well as access for existing medicines, the index also assesses research into new drugs. Here it found work on many tropical diseases was still neglected, an issue highlighted recently by the lack of drugs and vaccines for Ebola. While drug companies have been criticized over the years for not doing enough to ensure access in poor countries, the issue is moving up the agenda, with all top-20 companies having a board member responsible for access activities. Emerging markets are a growing focus for pharmaceutical companies as growth in Western markets slows. (Editing by David Clarke)