Anglo-Dutch oil company Royal Dutch Shell says it is continuing to work for the release of one of its mainland Chinese employees who is being held by the Chinese authorities on suspicion of stealing state secrets. 'We have tried a lot of different ways and measures to understand the situation, but so far we are getting nowhere,' Shell Hong Kong public affairs manager Albert Wong said. Xiu Yichun was detained in March, reportedly for gaining access to state secrets about a planned Chinese oil refinery project. 'The company, in Hong Kong, China and at the head offices in London and Holland, has been using different avenues to talk to the Chinese authorities both officially and unofficially to understand the specific causes of her detention,' Mr Wong said. He said the company did not know where Ms Xiu was being held, and had not been formally notified by the authorities of her detention.