Syntax error when using DECLARE within embedded SQL (WINDOWS)

I am trying to add some logic to my embedded sql by using an sql variable

EXEC SQL RELAXED
    DECLARE @PARM1 AS INTEGER
    SELECT
        CUSTOMER_KEY
    INTO
        :CUSTOMER_KEY
    FROM [db_owner].[CUSTFILE]
    WHERE ( CUSTOMER_KEY = CUSTOMER-KEY)
    ORDER BY CUSTOMER_KEY
END-EXEC

The compiler reports;

-->ERROR: syntax error at AS

Compiler switches are;

ccbl32 -Di -Zd -w -Zl -Zr -Pr -Ps -La -Li -Lf 

Is there anyway around this?