I write in reqard to the challenge that the Respondent has raised to your service as an arbitrator in this proceeding under the UNCITRAL Arbitration Rules. As explaind in our letter of October 23, 2007, a copy of which is attached herewith for your ease of reference, we consider the challenge to have been made within the time limit set out in Article 11(1) of the UNCITRAL Arbitration Rules.