Zimbabwe's new president Emmerson Mnangagwa has reportedly described his first 10 days in office as "hectic", but remained optimistic that his new team of ministers will turn around the economy of the country.

According to the state-owned Herald newspaper, Mnangagwa said this during a brief interview following the swearing in of 21 Cabinet ministers at the state house in Harare on Monday.

"It has been hectic, but I believe that with my team we will stand up to the challenge," Mnangagwa was quoted as saying.

AFP reported on Monday that Mnangagwa called for public unity to revive the country's sickly economy as his new cabinet took office.

"I have sworn in a new cabinet just to finish the term of the former president, which is a period of six to seven months," Mnangagwa said after the new ministers took the oath of office.

"I believe with my team we will stand up to the challenge."

"I want them (Zimbabweans) to be united, we must grow our economy," he added.

Mnangagwa was seen as favourite to succeed long-time ruler Robert Mugabe but then fell out with his boss.

Mugabe dismissed him after the then first lady, Grace Mugabe, accused him of plotting to topple her husband.

He briefly went into exile, returning after the army stepped in and the ruling party expelled Mugabe and a coterie of allies. The veteran ruler resigned on November 21 after 37 years in power.