SFTP max connection script help

[break time]

Hi All,
 
I want to limit the number of  simultaneous sftp connections to my RedHat 4 server. I believe OpenSSH had no options to set this limit.
 
Please give some directions how to accomplish this.
 
1/ Max sftp concurrent connections is 10
2/ The server will reject the 11th sftp connection, then send the message to client "SFTP server too busy - Please try again later"
 
Thank you !
 
bt