The joint House-Senate committee scrutinising the three Thai-Cambodian Joint Boundary Commission memorandums will ask for another 90 days to complete its work, panel secretary Ratchada Thanadirek said on Tuesday.
Ms Ratchada said a letter would be submitted to to Paliament President Chai Chidchob seek the extension to allow the committee to look into the three memos in full detail.
Representatives of all agencies concerned would be invited to give information to the committee because the documents on hand did not provide enough details.
Members of the committee would also travel to the border area to gather first-hand information, she added.
The joint committee reviewing the memos, comprising seven senators and 23 MPs, was initially given until Dec 1 to complete its job, she said.
Ms Ratchada said at this stage Thailand was not at a disadvantage because it was still in the stage of negotiation and surveying the area.
The people could rest assured that the parliament was duty-bound to protect the national interest and should not worry, she said.
The parliament agreed to set up the committee on Nov 2 when about 2,000 yellow-shirts of the People's Alliance for Democracy rallied to show strong opposition to the memos tabled for endorsement.
The PAD is concerned parliament's endorsement of the Thai-Cambodian memos, signed last year and in 2008 by the JBC, would result in a significant loss of territory to Cambodia.
PAD co-leader Sondhi Limthongkul said his group would rally on Dec 11 at Makkhawan Rangsan Bridge on Ratchadamnoen Avenue if it was not satisfied with the committee's review.
Prime Minister Abhisit Vejjajiva and Foreign Minister Kasit Piromya had reaffirmed the three JBC memos would not affect Thai sovereignty as it kept the territorial dispute between Thailand and Cambodia over the Preah Vihear temple on a bilateral, rather than a multi-lateral, level.