Trouble Creating Procedure With While Loop

Can anyone tell me why I cannot create a procedure with the following code in SQL Server 2000? For example I can run this in SQL Query Analyzer and it works:

                    
WHILE                      
(SELECT count(*) FROM testtable) > 0                    
                    
BEGIN                      
UPDATE testtable SET test_col = 'UPDATED'                      
    IF (SELECT count(*) FROM testtable) = 0                      
        BREAK                      
    ELSE                      
        CONTINUE                      
END                      

However whenever I add the line CREATE PROCEDURE TEST to create a procedure from the working code above it always fails with error 'Incorrect syntax near the keyword 'WHILE'.

i.e.

                    
CREATE PROCEDURE TEST                      
WHILE                      
(SELECT count(*) FROM testtable) > 0                    
                    
BEGIN                      
UPDATE testtable SET test_col = 'UPDATED'                      
    IF (SELECT count(*) FROM testtable) = 0                      
        BREAK                      
    ELSE                      
        CONTINUE                      
END                      

Server: Msg 156, Level 15, State 1, Procedure test, Line 2
'Incorrect syntax near the keyword 'WHILE'

Thanks in advance.