ereg_replace and \0

I don't know if this is a bug, but maybe someone has come accross this issue before. I was trying to use ereg_replace to insert \0 (character \ + character 0) into a string, but I was not able to do it since \0 has special meaning in the regex replacement string. The real problem is that if I try \\0 in the replacement string ("\\\\0" in PHP code) I get \\0 inserted into the string, insted of expected \0. Is there a way around this, or am I just missing something. Edin