The Pheu Thai Party yesterday rejected claims the draft amendment to Section 190 of the charter is aimed at granting the executive branch more power and serving the personal interests of ousted premier Thaksin Shinawatra.
Pheu Thai list-MP Korkaew Pikulthong said the amendment was proposed solely for the national interest.
Some low-level international trade and diplomatic agreements were being stalled unnecessarily due to the current version, he said.
However "ordinary" these agreements might be perceived, they need to be approved swiftly, he added.
Under the amendment, only international agreements that affect Thai territory or which involve free trade and investment would require parliamentary review, he said.
In its current form, the section requires House approval for all deals that significantly affect territory, sovereign rights, national economic or social security, or trade and investment deals with binding clauses.
Mr Korkaew insisted the amendment would not take power away from the legislature. He lashed out at critics of charter amendment for their attempts to involve the Constitution Court in the amendment process, accusing them of hypocrisy for undermining legislative power themselves.
The Pheu Thai MP also brushed aside Democrat Party claims that Thaksin would stand to benefit from the draft amendment.
The opposition party claimed Thaksin had personal interests in energy production in the Gulf of Thailand around areas in dispute with Cambodia.
Noppadon Pattama, a close aide of Thaksin, said the opposition's claim had been cooked up based on scraps of information. He confirmed Thaksin was interested in the energy sector, but said he was focused on other regions such as South America.