Speaking after a cabinet meeting yesterday to delegate responsibilities to deputy prime ministers, Ms Yingluck said none have been appointed to take charge of national security.
She said there would instead be an integrated operation to tackle security problems under the existing structure in which the Southern Border Provinces Administration Centre (SBPAC) and the Internal Security Operations Command (Isoc) will play key roles.
The prime minister said she has delegated responsibilities to her deputies to jointly tackle unrest in the far South.
Deputy Prime Minister and Education Minister Phongthep Thepkanchana has been assigned to supervise legal affairs and legal disputes, while Deputy Prime Minister Chalerm Yubamrung would supervise the SBPAC.
Mr Chalerm was also assigned to oversee the National Intellegence Agency and to be deputy chairman of the committee for strategic development of the southernmost provinces, of which the prime minister is the chairwoman.
The Isoc would come under the supervision of army chief Prayuth Chan-ocha.
Yutthasak Sasiprapa, who was recently removed from his role as deputy prime minister in charge of national security, would serve as Ms Yingluck's adviser as she tackles national security operations.
The inclusion of Mr Chalerm and Mr Phongthep in the security operation would help boost work efficiency in the command centre, the premier said.
She assured that there would be no coordination problems among those assigned to tackle the southern violence.
Mr Chalerm said it may not be necessary to appoint a deputy prime minister to direct national security operations, but all agencies must work together to develop security measures.
Chaisit Shinawatra yesterday denied he had been under pressure to quit the prime minister's advisory post to make way for Gen Yutthasak.
He said he decided to leave the post himself and his resignation had no political implications.
Gen Yutthasak said the prime minister, who serves as Isoc director, might assign him to assist work at the agency.
"I am ready to work, because of my intention and concern about the southern situation," the 78-year-old retired general said.
A source said the removal of Gen Yutthasak from a deputy prime minister post in the recent cabinet reshuffle caught him off guard.
He reportedly felt neglected and initially refused to take the advisory post.