Report on the last Exercise of Warrants (STEC-W No.18/2007)

Ref: ST/010/2007/0035 June 5th , 2007 Re: Report on the last Exercise of Warrants (STEC-W No.18/2007) 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.18 and on May 30th , 2007 as per following details: - Exercising ratio: 1 unit of warrant per 1 ordinary share. - Exercising price of STEC- W : Baht 1 per share. - Ordinary shares reserved to support the exercise of STEC-W: 1,292,610 shares. - No. of STEC-W holders exercise: 140 - No. of warrants being exercised of STEC-W No.18/2007: 1,076,690 units. - Ordinary shares resulted from the exercise of STEC-W No.18/2007: 1,076,690 shares. - Money received from the exercise of STEC-W No.18/2007: 1,076,690 Baht. - Total remaining warrants listed in the Stock Exchange of Thailand of STEC-W: 215,920 units. STEC-W expired and could not be used since May 31st,2007. Please be informed accordingly. Yours sincerely, Mr. Woraphant Chontong SEVP. Financial and Administration Division