Can we create pure functions in Fortran which generate random numbers?

My goal is to write a pure function using random numbers which can be used in a DO CONCURRENT structure. The compiler does not seem to permit this.

mwe.f95:8:30:

             call init_seed ( )
                              1
Error: Subroutine call to ‘init_seed’ at (1) is not PURE
mwe.f95:9:36:

             call random_number ( y )
                                    1
Error: Subroutine call to intrinsic ‘random_number’ at (1) is not PURE
mwe.f95:16:8:

     use myFunction
        1
Fatal Error: Can't open module file ‘myfunction.mod’ for reading at (1): No such file or directory
compilation terminated.

Why is this so and is there a way to generate random numbers in a pure routine?

The MWE follows. Compilation command is gfortran mwe.f95. Compiler version is GCC 5.1.0.

module myFunction

    implicit none

contains
    pure real function action ( ) result ( new_number )
        real :: y
            call init_seed ( )
            call random_number ( y )
            new_number = y**2
    end function
end module myFunction


program mwe
    use myFunction
    implicit none
    real :: x

        x = action ( )

end program mwe