Lt General Mahesh Senanayake, a battle-hardened officer who played a key role in defeating the Tamil Tigers during the brutal civil war, will be Sri Lanka's new army commander.

Senanayake was appointed by Sri Lankan President Maithripala Sirisena as the country's new army commander after being promoted to the rank of Lieutenant General, presidential secretariat officials said.

He is also a graduate of the prestigious United States Army Command and General Staff College and holds a Bachelor of Science (BSc) degree in Civil Engineering from Jawaharlal Nehru University in New Delhi.

He is currently serving as the Commander Security Forces in Jaffna. He was previously serving as the Chief of Staff (CoS) of the Sri Lanka Army.

He is a battle-hardened and illustrated officer from Sri Lanka's elite Special Forces who played a key role in defeating the Tamil Tigers in the three-decade-long civil war.

Senanayake's appointment was made a week after previous commander General Chrishantha De Silva was promoted to the post of Chief of Defence Staff of Sri Lanka, the country's top military post.

Three other appointments were also made by the Sri Lankan government.

Austin Fernando has been appointed to the post of Presidential Secretary.

Fernando previously held the post of the Governor of the Eastern Province. He played a crucial role as the Secretary to the Ministry of Defence during the peace negotiations between Sri Lankan government and the LTTE in 2002-2004.

Rohitha Bogollagama, the former foreign minister of Sri Lanka, has been appointed as the new Governor of the Eastern Province.

Bogollagama was previously chief organiser of Sri Lanka Freedom Party. He had also served as the Cabinet Minister of Foreign Affairs from 2007 until he was defeated in the General Elections held in 2010, losing his seat in parliament.

Kapila Waidayarathne has been appointed as the New Secretary to the Ministry of Defence.

Waidyarathna, former Senior Additional Solicitor General is the third secretary appointed to the Ministry of Defence since Sirisena, who is also the Minster of Defence, assumed office in 2015.