How do I get utf-8 support with PCRE?

I am having problems building lucene index using Zend_Lucene. I get the following error


PHP Notice:  iconv(): Detected an illegal character in input string in /var/www/ZendFramework-1.5.2/library/Zend/Search/Lucene/Analysis/Analyzer/Common/Text.php on line 56

Thanks in advance.
Regards,
Amitava Shee