Additional clarification on Autoclaved Co.,Ltd. Investment

Ref: ST/010/2004/0006 February 10, 2004 Re: Report on the Investment Policy To: The President of The Stock Exchange of Thailand Ref: Letter of The Stock Exchange of Thailand reference no. Bor Jor. 87/2547 According to your letter reference number Bor Jor. 87/2547 dated on 5th February, 2004 requesting Sino-Thai Engineering and Construction Public Company Limited to clarify our investment policy in the Autoclaved Aerated Concrete Product Company Limited that engages in business of producing and selling autoclaved aerated concrete products and all types of concrete products, as stated in the reference letter. The Company would like to report further information as follows: Q.1) Investment Policy in Autoclaved Aerated Concrete Product Company Limited and explain the reason of having both STECON and Perpetual Prosperity Company Limited, the company owned by Mr. Anutin Charnvirakul, as the shareholders of Autoclaved Aerated Concrete Product Company Limited. A. 1) Autoclaved Aerated Concrete Product Company Limited was initiated by Concrete Chonburi Product Public Company Limited and Mr. Anutin Charnvirakul was invited to invest the project at the commencement. Later on when STECON has learnt about the project and believed that the project has a good business potential, STECON then approached to invest in Autoclaved Aerated Concrete Product Company Limited. Decision makings of STECON and Perpetual Prosperity Company Limited in investing in Autoclaved Aerated Concrete Product Company Limited are totally independent from each other. Q. 2) Relationship between STECON and National Union Company Limited in terms of common large shareholders, directors, and executives by stated shareholding ratio, title in each company, and business relation. A. 2) The Company would like to inform that The Company and National Union Company Limited do not have any common large shareholders, directors, and executives. Both Companies have no related business between them. It is therefore, informed for your acknowledgement and dissemination to the public and other investors. Sincerely Yours, Mr. Woraphant Chontong (SVP) Finance and Accounting Division