I'm Pakistani, need a visa to attend yarn expo fair in Shanghai on 28th to 30th Aug, how can I get a visa on urgent basis?

i need chinese visa on urgent basis, i want to attend yarn expo fair in shanghai on 28th to 30th of Aug.i need chinese visa for that purpose, if i get invitation letter from any chinese company, a letter attested with the foreign ministry then it would be easy for me but that would take more then 30 days. i need urgent visa in maximum 10 days or so, what would be the procedure and how that could be done?