ofxstatement is a tool to convert proprietary bank statement to OFX format, suitable for importing to GnuCash. Plugin for ofxstatement parses a particular proprietary bank statement format and produces common data structure, that is then formatted into an OFX file.
Users of ofxstatement have developed several plugins for their banks. They are listed on main ofxstatement site. If your bank is missing, you can develop your own plugin.
$ ofxstatement convert -t ingbe input.csv output.ofx