Import nested classes into namespace - C++

Say I have a class like this:

class A {
public:
    class B {
        // ...
    };
    static void f();
    // ...
};

I can refer to B as A::B and to f() as A::f(), but can I import B and f() into the global/current namespace? I tried

using A::B;

but that gave me a compilation error.