Thai Prime Minister Prayut Chan-o- cha said Tuesday that former premier Yingluck Shinawatra had acquired permission from the coup-making National Council for Peace and Order before leaving for Japan on Sunday night.

Prayut said he would not interfere in the trip, during which Yingluck reportedly will spend about three days in Japan and then join a merit-making ceremony in India before returning to Thailand next Sunday.

He is not concerned about expected meetings between Yingluck, her brother and exiled former prime minister Thaksin Shinawatra and former Pheu Thai Party politicians, Prayut added.

This is the second overseas trip that Yingluck has made since the May 22 coup toppled her government.

It remains under the spotlight whether she will survive a case in which the National Anti-Corruption Commission (NACC) has accused her of dereliction of duty in overseeing a controversial rice-pledging scheme.

The already-suspended scheme, a flagship "populist policy" of the Yingluck government, has been accused of breeding corruption and incurring great losses, while Yingluck has been blamed for condoning corrupt practices.

If found guilty, Yingluck could face a jail term as well as a five-year ban from politics.

Earlier this month, the NACC recommended the National Legislative Assembly, the interim legislature, to impeach the former premier.

In the meantime, it has yet to reach an agreement with the Office of the Attorney-General (OAG) on whether there are sufficient grounds for pressing charges against Yingluck in the Supreme Court's Criminal Division for Holders of Political Positions.

The NACC and OAG is scheduled to meet for the third time on Nov. 7 to settle their differences concerning the case. The NACC has been advised to interview more witnesses to collect more information.