R and unix tool 'screen'

I have problems running R with screen. For those who don't know,
screen is a unix tool that is quite handy if you want to leave
a process (that outputs to tty) running when you logout, and
then recover the session later on.

It works like this:
1) run 'screen': you get a normal prompt as if you were in a normal
shell.
2) run whatever command you like
3) press 'C-a d' to detach the session. Now you can logoff if you like
4) when you want to recover the session type 'screen -r'

The problem is that R seems to catch the 'C-a' signal, and nothing happens.
Since there is no way to detach the screen, there is no use to it either.

Is there a way around this problem?

Giampiero