32 bit C++ problem on amd64 - std lib includes missing?

[hopper]

Hi all

I am using 5.10 amd64 to build a bunch of C & C++ code. All development and library packages are included (as far as I know) including the 'ia32' 32-bit libraries. All C and C++ builds are fine with both gcc-3.4 and gcc-4.0 on amd64. C code compiles, links and runs fine on 32-bit too. However, C++ will not even compile:

/usr/include/c++/4.0.2/iostream:43:28: error: bits/c++config.h: No such file or directory
In file included from /usr/include/c++/4.0.2/ios:43,
from /usr/include/c++/4.0.2/ostream:44,
from /usr/include/c++/4.0.2/iostream:44,
from bgp_objects.cpp:10:
/usr/include/c++/4.0.2/iosfwd:45:29: error: bits/c++locale.h: No such file or directory
/usr/include/c++/4.0.2/iosfwd:46:25: error: bits/c++io.h: No such file or directory

etc.. etc..
I believe this is because the 32-bit C++ standard library includes are not present:

mwh $ locate bits/c++io
/usr/lib/gcc/i586-mingw32msvc/3.4.2/include/c++/i586-mingw32msvc/bits/c++io.h
/usr/include/c++/3.4/x86_64-linux-gnu/bits/c++io.h
/usr/include/c++/4.0.2/x86_64-linux-gnu/bits/c++io.h
Have I missed something or is this a problem with the package installer setup? Is there a straightforward workaround?

TIA

Michael