Need to search a content which is in greek letters using strtoupper and strtolower

[madebynoodle]

I am currently working in a GREEK project. In that project all the contents are GREEK and in that i have a search functionality. Search process is good. But strtoupper() didn't convert the Greek language to upper case and strtolower() didn't convert the Greek language to lower case. But for English language its working fine. Is there any possible way to convert the Greek letters to UPPER and LOWER case.thanksFero