[debian] locale.gen fails

[arne anka]

just noticed that somehow my locales are gone.
when trying to recreate them, locale.gen ends up with
Generating locales (this might take a while)...
   en_DK.UTF-8...cannot map archive header: Invalid argument
  done
   en_US.UTF-8...cannot map archive header: Invalid argument
  done
Generation complete.

and no locales are available.
locale -a
as root

C
POSIX

as normal user

locale: Cannot set LC_CTYPE to default locale: No such file or directory
locale: Cannot set LC_MESSAGES to default locale: No such file or directory
locale: Cannot set LC_COLLATE to default locale: No such file or directory
C
POSIX

any hints? i so far found only reports of this porblem but no answer at  
all.