Prime Minister Prayut Chan-o-cha said the four ministers who concurrently serve as executives of the newly established Palang Pracharath Party have not broken the law by assuming dual roles.
Gen Prayut said Tuesday it was their personal decision to engage in political party activities.
He said when they asked him for permission to join the party, he warned them not to mix party affairs with their ministerial duties, as it could undermine the national administration.
Gen Prayut said the four ministers were not key decision-makers in the cabinet.
However they are facing calls to step down as criticism mounts over potential conflicts of interest after they assumed executive posts at Palang Pracharath. The party has long been speculated as a political vehicle for the regime, and possibly for securing Gen Prayut's comeback as prime minister after the election that could come as early as late February.
At the party's first general assembly on Saturday, Industry Minister Uttama Savanayana was made party leader, Science and Technology Minister Suvit Maesincee was named deputy leader, Commerce Minister Sontirat Sontijirawong was appointed secretary-general, and PM's Office Minister Kobsak Pootrakool was given the role of spokesman.
Mr Uttama, Mr Sontirat, Mr Suvit and Mr Kobsak are all members of the government's economic team led by Mr Somkid.
A source at the cabinet meeting said Gen Prayut told the four ministers not to exploit their ministerial roles to gain an unfair advantage over other politicians in the lead-up to the poll.
The prime minister also stressed the need for them to ensure the public can distinguish between the new party's name and the government's Pracharath people-state partnership development programme.
Even though the names are the same, the party does not necessarily share the same policy line as the government, the source quoted Gen Prayut as saying.
Mr Sontirat admitted things could get tough for him and that he would have to tread carefully after deciding to enter the political fray. "I have a lot to prove and have to work harder," the commerce minister said.
Asked when he would choose to "wear only one hat", Mr Sontirat promised his role as a politician would exceed the standards set by earlier politicians.
Questions were also asked by critics as to whether he would step down from his ministerial post after the National Council for Peace and Order (NCPO) lifts the ban on political activities. Mr Sontirat only said: "Let's wait and see."
The NCPO is expected to lift the political activities ban in December to allow parties to fully prepare for the general election. It eased some political restrictions to permit certain political activities last month.
Mr Sontirat said he may have to consider whether to attend cabinet trips to the provinces after he assumes the helm of Palang Pracharath because he could come under fire for using them and public office to woo votes for the party. Critics see the trips as veiled canvassing.
- Editor's comment: Rumour mill at full speed
- EDITORIAL: Political ministers must resign