CHINA has promised to inform Hongkong immediately if an emergency occurs at the Daya Bay nuclear plant, legislators heard yesterday. Guangdong's contingency office - which would receive all information in relation to the plant - would make all ''appropriate decisions'' if there was an accident, Principal Assistant Secretary for Security, Frankie Lui Kin-fun, told the Environmental Affairs Panel meeting. According to standards set by the International Atomic Energy Agency, a country must inform its neighbours of nuclear accidents that may affect them. But independent legislator Emily Lau Wai-hing questioned whether the rules would apply to Hongkong after 1997. United Democrat legislator, the Reverend Fung Chi-wood, asked if Hongkong could release details of an emergency to the outside world as a minority shareholder in the joint venture project. Dominic Tai Kuen-kwan, of Hongkong Nuclear Investment Company, said: ''There are no restrictions on Hongkong to release information. ''But if an emergency occurs, it is better to have only one source of information, in order to eliminate the flow of rumour and wrong information.''