Teamcity and SSH RSA Key

I am running plink from a command line build step.

The remote server is prompting to accept the key, but I can obviously not do this while Teamcity process is running.

When I drop into a command prompt (windows) and run the same plink command I got the prompt and accepted the key. I then go back to Teamcity and retrigger my build task. I can still see in the log file that the remote server is prompting me to accept the rsa key.

Why would Teamcity process environment not see that I have already accepted the key? Subsequent attempts to use plink from the command line do not require me to re-accept the rsa key, but Teamcity still gets the prompt.

Please help