Writing a library with C and C++ interfaces, which way to wrap?

When preparing a library (let's call it libfoo), I find myself presented with the following dilemma: do I write it as a C++ library with a C wrapper:

namespace Foo {
  class Bar {
    ...
  };
}

/* Separate C header. #ifdef __cplusplus omitted for brevity. */
extern "C" {
  typedef void *FooBar;
  FooBar* foo_bar_new() { return new Foo::Bar; }
  void foo_bar_delete(FooBar *bar) { delete bar; }
}

Or is it better to write it as a C library with a C++ wrapper:

/* foo/bar.h. Again, #ifdef __cplusplus stuff omitted. */

typedef struct {
  /* ... */
} FooBar;

void foo_bar_init(FooBar *self) { /* ... */ }
void foo_bar_deinit(FooBar *self) { /* ... */ }

/* foo/bar.hpp */

namespace Foo {
  class Bar {
    /* ... */
    FooBar self;
  }

  Bar::Bar() {
    foo_bar_init(&self);
  }

  Bar::~Bar() {
    foo_bar_deinit(&self);
  }
}

Which do you prefer, and why? I favour the latter because it means I don't have to worry about my C functions accidentally having exceptions bubble up, plus I prefer C as a language as I feel that it's a smaller semantic minefield. What do other people think?

EDIT: So many good answers. Thanks all. It's a shame that I can only accept one.