4. If the challenge is not made in accordance with the provi­sions of the previous paragraph, the right to bring a challen­ge on these grounds shall be barred thereafter in the arbitral proceedings or in proceedings before a court.

5. The arbitral tribunal may suspend the arbitral procee­dings as of the day of receipt of the notification from the challen­ging party.

6. Withdrawal by a challenged arbitrator shall not be inter­preted as acceptance of the grounds for the challenge.

7. If the challenged arbitrator does not withdraw within two weeks * after the day of receipt of the notification from the challenging party, the Executive Board shall promptly decide in writing on the merits of the chal­lenge. The Executive Board may give the challenged arbitrator and the parties the oppor­tunity to be heard. The decision shall be communicated by the Administrator to the parties and the arbitrator(s).