Unmappable character for encoding ASCII

I'm getting the following error when trying to build my project within IU-123.67 on Mac OS X:

RegistrationDetails.java:37: error: unmappable character for encoding ASCII
java:     @Pattern(regexp = "[A-Za-z0-9@#$��&+=]{8,12}")

The java source is UTF-8 encoded and contains:
@Pattern(regexp = "[A-Za-z0-9@#$£&+=]{8,12}")

Tried adding additional command line parameter "-encoding UTF-8" to comiler options but doesn't help.