"The reshuffle was made for appropriation. I would take responsibility for the decision," he said on Friday.
Krit Kraichitti from the Economic Affairs Department who replaced Virachai was the right person since he was a former director of the legal affairs department, the minister said.
The cabinet has already endorsed the reshuffled since Tuesday.
A ministry source said Virachai was transferred to an inactive post since he refused to give to Noppadon a copy of documents concerning the purchasing contract of the CTX explosive detection which Foreign Ministry translated for Assets Examination Committee.
AEC has been investigating a corruption charge against ex-prime minister Thaksin Shinawatra and his associates over the purchase to the CTX bomb detectors.
Noppadon was a former spokesman and personal lawyer of Thaksin.
The junta-installed AEC would make the final decision on Monday whether to indite to indict Thaksin and his associates over the corruption case. However, Noppadon said the motivation behind his decision was the Ministry's internal affairs.
"I don't want to disclose inside information which could damage our ministry's reputation but I can guarantee the reshuffle has nothing to do with the CTX case," he said.
Earlier, Permanent Secretary Virasak Futrakul issued an open letter to the officials of the Legal Affairs Department to give moral support to Virachai who he said has worked with honesty and integrity.
Virachai has shown his diplomatic skills and talents in negotiation with Laos and Cambodia to protect national interest of the country while he was in the position, Virasak said in the letter.
"He would work well in the new position (an ambassador attached to the ministry) as a legal advisor to the permanent secretary and he is the model for all staffers at the legal affairs department," the permanent secretary said in the letter.