C# – IronPython invocation from C# (with SciPy) fails with ImportException: “No module named mtrand”

I have a python library I am trying to use via IronPython (v2.7 RC1 [2.7.0.30]) invocation from C# application. The library uses NumPy and SciPy quite extensively, which does work with SciPy and NumPy for .NET when ran using ipy from command line like this:

ipy.exe -X:Frames file_from_lib_importing_numpy.py

However, when I invoke IronPython from C# using the code below, an exception is thrown:

ImportException
"No module named mtrand"
   at Microsoft.Scripting.Runtime.LightExceptions.CheckAndThrow(Object value)
   at IronPython.Runtime.Operations.PythonOps.ImportStar(CodeContext context, String fullName, Int32 level)
   at Microsoft.Scripting.Interpreter.ActionCallInstruction3.Run(InterpretedFrame frame)
   ...
   at Microsoft.Scripting.SourceUnit.Execute(Scope scope, ErrorSink errorSink)
   at Microsoft.Scripting.Hosting.ScriptSource.Execute(ScriptScope scope)
   at Microsoft.Scripting.Hosting.ScriptEngine.ExecuteFile(String path)
   at Microsoft.Scripting.Hosting.ScriptRuntime.ExecuteFile(String path)
   at Microsoft.Scripting.Hosting.ScriptRuntime.UseFile(String path)
   ...

The C# code (a part of it) that invokes IronPython is as follows:

    ScriptEngine _engine;

    var opts = new Dictionary<string, object>();
    opts["Frames"] = ScriptingRuntimeHelpers.True;
    _engine = Python.CreateEngine(opts);

    var sp = _engine.GetSearchPaths();
    sp.Add(@"c:\Program Files\IronPython 2.7");
    sp.Add(@"c:\Program Files\IronPython 2.7\DLLs");
    sp.Add(@"c:\Program Files\IronPython 2.7\Lib");
    sp.Add(@"c:\Program Files\IronPython 2.7\Lib\site-packages");
    sp.Add(_path);
    _engine.SetSearchPaths(sp);

    var _runtime = _engine.Runtime;
    var scope = _runtime.ExecuteFile(Path.Combine(_path, "mytest.py"));

For testing purposes I am executing the following file 'mytest.py':

    import sys
    sys.path.append(r'c:\Program Files\IronPython 2.7')
    sys.path.append(r'c:\Program Files\IronPython 2.7\DLLs')
    sys.path.append(r'c:\Program Files\IronPython 2.7\Lib')
    sys.path.append(r'c:\Program Files\IronPython 2.7\Lib\site-packages')

    import os, os.path
    cd = os.path.dirname(__file__)
    if not cd in sys.path:
        sys.path.append(os.path.dirname(__file__))

    import numpy as np
    print 'OK'

    x = np.array([1,2])
    print x

Which fails on the line 12 'import numpy as np'.
The problem is that the file __init__.py in IronPython 2.7\Lib\site-packages\numpy\random\ contains the following line

from mtrand import *

which fails. Note that the mtrand is not a module, it is a directory.
I can not think of anything else I can try to make this work, so I would very much appreciate any help from you.
Thank you very much.