ssh: Could not resolve hostname github.com:loremfoobar: Name does not resolve

[LoremFooBar]

I am trying to mirror a Bitbucket repo to GitHub. I added the public key as access key in BB and as deploy key with write permissions in GH. I am running the following command:

docker run 
    -e SRC_REPO=git@bitbucket.org:loremfoobar/reportgenerator-coverage-bitbucket-pipe.git 
    -e DEST_REPO=git@github.com:loremfoobar/reportgenerator-coverage-bitbucket-pipe.git 
    -e DEST_DEPLOY_KEY=<base64 private key> 
    -e SRC_DEPLOY_KEY=<base64 private key> 
    -p 8181:8080/tcp 
    karser/gitbitlabhub

The source BB repo is successfully cloned, but when the push command runs there's an error message:

+ git push --prune dest '+refs/remotes/origin/*:refs/heads/*' '+refs/tags/*:refs/tags/*'
ssh: Could not resolve hostname github.com:loremfoobar: Name does not resolve
fatal: Could not read from remote repository.

Any idea what's wrong?