The Indonesian government would take measures to prevent the spread of the new strain of avian influenza virus, which is more virulent, official said here on Wednesday. The step was taken following the finding of the new clad of H5N1 virus after the death of over 320,000 ducks in some provinces in Java island was reported since November. Indonesian Trade Ministry would conduct tighten control over distribution of poultry to outside of Java island, said Deputy Trade Minister Bayu Krisnamurthy. \"We are cautious about the movement of poultry in Java. We must watch closely the movement of chickens and ducks (from Java island) . We must control it,\" he said. Bayu asked the quarantine agency to control and supervise the distribution of the poultry from Java island to outside of the islands. \"We must made a quarantine for the poultry,\" he said. Indonesia is an archipelago country with some 17,500 islands, where Java island is one of the five main islands. Indonesia has been investigating the origin of the new clad, which is very different from the clad of H5N1 virus found in recent years. The agriculture ministry said that the cause of the emerge of the news strain may be drift mutation or genetic shift from the previous viruses or importation of poultry from overseas. Indonesia has been hit hardest by bird flu since 2003, the virus has killed 160 people out of 192 cases since 2005, according to health ministry. But, so far the new strain of H5N1 virus on ducks has not caused human fatality, the ministry said.