Both are correct with different meanings according to the situations. #我不能说中文, it means "I can't speak Chinese". #我不会说中文 means "1. I am not able to speak Chinese" or "2. I won't speak Chinese"

Sorry. I meant to say "参加一个会议" rather than "参见一个会议". That was a slip of the pen. Hope it didn't confuse you

"我不会说中文" is better.

"我不会说中文" is correct. 但有时得说“我不能说中文”。比如，我是一个中国人，要参见一个国际会议，我可能对别人说：“明天我要参见一个会议。那是个国际会议，我不能说中文。”It means that I will have to speak some language other than Chinese (Possibly because it's a rule. Possibly because most of people who will attend the meeting don't understand Chinese and there will be no interpreter)

我不会说中文。