"The Department of Agriculture (DoA) has come up with the initiative to launch this study because we need to boost the country's trade opportunities," said the department's deputy director-general Suwit Chaikiattiyos.
His department is under the supervision of the Ministry of Agriculture and Cooperatives.
Suwit said 27 countries permitted open-field GM trials and made profits based on experimental results.
He said GM plants allow growers to increase yields, control costs and cut pesticide use.
"Yet at this point we remain unsure whether open-field GM trials will pave the path for fully-driven GM agriculture for Thailand," he said.
Suwit said according to a 2007 Cabinet resolution, GM experiments are allowed only on government land and only when conducted under the supervision of relevant government agencies.
"This makes the GM experiment process complicated," he said.
He said a feasibility study currently underway was subject to further review.
"We will have to weigh the pros and cons," he said.
While his department claims to have observed many good things about GMO, non-governmental groups say they have not.
Many NGOs feel GMOs do more harm than good.
Witoon Liemchamroon, director of the Biothai Foundation, warned that GMOs could spread to other farmland and contaminate crops.
"It has happened before," he said, citing the case in which papaya plants and seeds "leaked" from an experimental field in Khon Kaen.
Upset by the contamination, Greenpeace filed a complaint against the DoA. This decade-long battle is still pending in the Supreme Administrative Court.
Witoon believed that the government would not be able to control the contamination.
In his eyes, GMOs pose a threat to the country's export sector when it comes to agricultural produce.
"Many foreign countries have not yet accepted GMO products. Among them are the European Union members and Japan, which are big buyers of Thai crops," Witoon said.
He said last year Japan recalled GM papayas from Thailand, which affected 26 export companies.
Open-field GM trials should only be attemped after the Biosafety Bill is passed, he said. The bill is still being considered by the Ministry of Natural Resources and Environment.
"After the bill becomes an Act, those held responsible for causing contamination will be required to pay compensation for GM-caused damages," he said.
Theera Wongcharoen, from the National Farmers Council, said farmers could face legal action for infringing GMO copyright and patents if there was widespread contamination.
In September, a large number of farmers staged nationwide protests after the DoA and the Ministry of Commerce decided to jointly study a feasibility study to genetically develop the four economic crops and carry out GM open-field experiments.
"If the plan is still going ahead, the farmers will continue to oppose this policy until it is called off," Theera said.
Witoon echoed Theera's concerns and warned that farming costs may increase as a result of the mandatory examination of a contamination.
"Many farmers have to spend higher cost to monitor their farm products to ensure that they won't get contaminated. Otherwise, no one will buy them," he said.
But Jessada Denduangboripant, a prominent lecturer at Chulalongkorn University's Faculty of Science, voiced support for development of GM crops. He described them as a good export option for the agricultural sector as it would benefit the economy.
"GM plants are important because they are more resistant to plant epidemics," he said.
"This was evident in an experiment the DoA did in 2003 as a result of the papaya epidemic in 1975," he said.
With widespread GM farming, he said Thailand would not have to rely on imported farm products such as GM corn seeds from the Philippines that were used for animal feed.
He said open-field GM trials would deliver more accurate results compared with close-field trials.
"An open-field experiment is necessary," he said. "Results will prove whether GM plants are counterproductive or beneficial. "It's just that for now people need to be more open-minded."