Mainland bird's nest merchants accused of selling fake or tainted products staged a press conference with Malaysian officials to defend their reputation. But the event itself was a sham and the officials were bogus. The press conference was held in a hotel in Hangzhou on July 26. Two foreign men wearing colourful shirts posed as officials from Malaysia, a major supplier of bird's nests to China. The event came at the height of a crackdown by the Zhejiang authorities on fake or substandard red blood bird's nests - a delicacy used in soup. Red blood bird's nests, produced by a certain type of swallow, are more expensive than white bird's nests because they are rarer. The province's Industry and Commerce Administration said it had randomly tested 200kg of red blood bird's nest products in 303 batches. All were substandard and some contained up to 10,000 milligrams (10 grams) of nitrite per kilogram, 350 times the maximum amount permitted by national food additive safety standards. Some bird's nest merchants admitted they had coloured white bird's nests artificially to make them look like red blood bird's nests - named for their colour - but the process left large amounts of nitrite in the products, the administration told a press conference on Monday. Zhejiang authorities said they were alerted by online postings by journalists about a bogus press conference, purportedly attended by the National Endangered Species Import and Export Administration of Malaysia and the Export Quarantine Administration of Malaysia. An investigation by Xinhua found that there were no such agencies in Malaysia. At the bogus press conference, the fake officials, accompanied by people purporting to be bird's nest merchants, said nitrite could be removed easily by soaking bird's nests in water. They also denied that some red blood bird's nests were fake. The identity of the organiser of the press conference remains unknown. The industry and commerce agency said on Monday that it believed merchants from Xiamen were behind it. An official said there was little the administration could do to punish the organisers of the press conference because it was responsible for clamping down on fake goods, not fake press conferences. Shen Xiaocong, a brand manager for Xiamen Shuangdanma Industrial, said his company had not been involved in the phoney event and was concerned about its impact. However, he did not agree with the administration's findings of 'excessive' nitrite levels in bird's nest products. 'Nitrite is present in all bird's nest products everywhere, but it's not in any way an additive, so the administration was not justified in applying the national food additive safety standard to testing,' he said. Upmarket delicacies like bird's nest and abalone are increasingly popular among affluent mainlanders. Red blood bird's nests costs 10 yuan (HK$12) to 30 yuan a gram on the mainland.