Turkey's new government announced late on Monday the appointment of former chief of staff General Hulusi Akar as defence minister, a rare transition from military ranks to the political realm.

Erdogan then appointed ground forces commander General Yasar Guler as chief of staff by presidential decree published in the official gazette.

With more than 900,000 active personnel, Turkey has the second largest force in NATO after the United States which has almost 1.5 million.

The announcement comes as NATO meets in Brussels amid tensions over spending.

Erdogan was sworn in Monday for a second presidential term under a controversial new system that will centralise all institutions, including the army, under the presidency.

Erdogan was granted sweeping powers in the new executive presidential system, meaning he can directly appointing top military figures.

Under the new decree, Erdogan will decide on the promotion of top army officers including colonels, brigadier generals, admirals and generals in the Turkish armed forces.

The official appointment of the army officers usually takes place on August 30 every year. The term of duty for the top army general is four years.

Guler, 64, along with Akar and top commanders, had been abducted to a military base by the putschists on the night of the 2016 coup aimed at unseating Erdogan's government.

Ankara accuses US-based Muslim preacher Fethullah Gulen of masterminding the coup bid -- a charge he strongly denies.

Turkey has launched a massive purge aimed at ending Gulen's influence, dismissing thousands of soldiers including half the pre-coup contingent of generals.

According to the new decree, deputy chief of staff General Umit Dundar was appointed land forces commander.

Dundar played a key role in thwarting the coup attempt. In a live statement to television channels on the night, he said: "That is a movement not supported by the Turkish armed forces."

Erdogan has since defeating the coup bid increased his influence over the armed forces, who had previously been seen as a parallel power structure that had repeatedly ousted governments.