visa requirements for philippines passport holder in Qatar

hi
i am a Filipino staying and working in Qatar, my employer ask me to go and attend the China Import & Export Fair this April 25 until May, I have the invitation from the said fair and the ID confirmation, but the Chinese embassy in Qatar asked for local government approval of the said invitation from Chinese local government, how can I obtain this document as I'm running out of time, any agency suggestions? or can I obtain entry permit from chinese airport upon arrival? even for 3 days just for the exhibition? please needs urgent help and thanks