Report on the Exercise of STEC-W No.15 and STEC-W2 No.6

Ref: ST/010/2006/0066 October 2nd , 2006 Re: Report on the Exercise of Warrants (STEC-W No.15/2006, STEC-W2 No.6/2006) To: The President The Stock Exchange of Thailand Sino-Thai Engineering & Construction Public Company Limited would like to report the exercise of STEC-W No.15 and STEC-W2 No.6 on October 2nd , 2006 as per following details: - Exercising ratio: 1 unit of warrant per 1 ordinary share - Exercising price of STEC-W : Baht 1 per share - Exercising price of STEC-W2 : Baht 8.50 per share - Ordinary shares reserved to support the exercise of STEC-W: 1,810,750 shares, and STEC-W2: 163,548,461 shares - No. of STEC-W holders exercise: 2, STEC-W2 exercise: 0 - No. of warrants being exercised of STEC-W No.15-2006: 4,200 units, and STEC-W2 No. 6/2006: 0 unit - Ordinary shares resulted from the exercise of STEC-W No.15/2006: 4,200 shares, and STEC-W2 No.6/2006: 0 shares - Money received from the exercise of STEC-W No.15/2006: 4,200 Baht, and STEC-W2 No.6/2006: 0 Baht - Total remaining warrants listed in the Stock Exchange of Thailand of STEC-W:1,806,550 units, and STEC-W2:163,548,461 units Please be informed accordingly. Yours sincerely, Mr. Woraphant Chontong SEVP. Financial and Administration Division