MP Panich Vikitsreth was detained on Wednesday 29th December, along with a group of journalists and members of the 'Yellow Shirt' movement, a group which advocates a tough stance on border disputes with Cambodia.
Panich told reporters by telephone that the group was only inspecting the contested border region of Thailand's Sa Kaew province and Cambodia's Banteay Meanchey province. Video footage released 4th January, however, shows Panich making a phone call to his secretary, asking that Thai Prime Minister Abhisit Vejjajiva be informed, through his secretary Somkiat Krongwatanasuk, that the group was in Cambodia.
"Please tell Somkiat to inform the prime minister that we are already inside Cambodia. I planned to call the prime minister myself but it is okay now," Mr Panich says on the phone to his secretary.
"Call him [Somkiat] so in case there are problems, we can coordinate because we are already in a Cambodian area. And make sure that he does not tell anybody because only the prime minister must know this."
The video footage is seen as contradicting claims that Abhisit did not know about the trip, as well as claims that the group did not cross the border into Cambodia. Abhisit has admitted on 4th January that he sent Panich to the border region, but that he did not know exactly where the group would go.
The Thai foreign affairs ministry has said that the team was sent to investigate complaints from local residents that they could not make a living on the land, and that they sincerely believed they were on Thai soil, despite video evidence to the contrary.
Thailand sent its foreign minister, Kasit Piromya, to Phnom Penh to try to seek the release of the group. They have already appeared in a Phnom Penh court, on 30th December, charged with illegal entry and illegally entering a military base along the border. They could be sentenced to up to 18 months in prison.
Abhisit has called for their immediate release and said any cases concerning disputed border areas should be settled out of court. "If Cambodia wants to maintain good and smooth ties, we should stick to our commitment to talk and work together," he told reporters in Bangkok.
Cambodian Prime Minister Hun Sen has hit back, however, saying, "They were measuring Thai territory inside Cambodian territory. So Cambodia has the right to arrest them,"
Hun said he hoped the incident would not affect relations between the neighbours.
"I hope Prime Minister Abhisit will understand the Cambodian judicial system," he said, adding that the arrests were "not revenge" against Thailand.
Most of the arrested men are members of the People's Alliance for Democracy (PAD), better known as the 'Yellow Shirts'. In November, the Yellow Shirts held a rally outside the parliament in Bangkok, calling on the Thai government to take a tougher stance against Cambodia over the border issue.
This issue has received much attention in both Cambodia and Thailand, and on 1st January, representatives from the Thailand Patriot Network submitted a letter to UN Secretary-General Ban Ki-moon, asking for justice, humanity and respect for the civil rights of the seven Thais. There are rumours that the Yellow Shirts are planning a rally on 4th January in the border region where the group was picked up.
It seems that neither side has increased border security in response to the situation.