The word laboratory can be translated either as مختبر mukhtabar (plural مختبرات mukhtabaraat), or معمل ma'mal (plural معامل ma'aamil). Mukhtabar is more formal and accurate, but may not be understood by the average person in some regions. Ma'mal is also correct, but in some regions it means "factory".

For cooperation, I used the combination الهيئة التعاونية alhay`ah alta'awuniyyah, which means "the cooperative institution". Some people will use التعاونية alone. Although it is an adjective, but with frequent usage it may become acceptable.

The reverse translation of my suggestion is "The International Cooperative Institution for Accreditation of Laboratories".

Of course the best answer is to find if that organization already has an Arabic title by which it goes, may be someone here will find it.

Regards,

Alaa Zeineldine