By Paul Carsten and Deepa Seetharaman BEIJING/SAN FRANCISCO (Reuters) – Alibaba is taking a tougher line against counterfeit items sold on its online marketplaces as the Chinese e-commerce giant heads towards a U.S. stock listing that could be the worlds biggest technology company IPO. Some security experts say the Chinese groups stricter standards on piracy and fake goods may even surpass those of Amazon.com Inc and eBay Inc. In its IPO filing last week, Alibaba Group Holding Ltd said the perception that its sites are cluttered with counterfeit items could hurt its ability to win over customers, investors and U.S. retail partners. Two days after contacting Alibaba, the supplier of the counterfeit had been removed. \They reached out to the supplier and told them they couldnt do that,\ said De Arkos, CEO of U.S. company Innovative Watersports that has sourced through Alibaba since 2012.