Zimbabwean President Emmerson Mnangagwa has delivered his first state of the nation address. File picture: Shaun Jusa/Xinhua

Harare - Zimbabwe's new President Emmerson Mnangagwa has vowed to ensure free and fair elections, as well as make the country's troubled economy attractive to investors, in his first state of the nation address.

The leader known as "the Crocodile" replaced long-time president Robert Mugabe in the wake of a November military coup.

"My government is committed to entrenching a democratic society driven by the respect for the constitution, the rule of law, mutual tolerance, peace and unity," Mnangagwa told parliament on Wednesday.

Zimbabweans were euphoric after Mugabe was ousted, but many quickly became doubtful he would provide any meaningful change after he appointed a cabinet full of Mugabe-era politicians.

Last week Mnangagwa's special adviser and war veteran leader Christopher Mutsvangwa told the media that the ruling Zanu PF party would work with the military to ensure victory in the 2018 elections.

Mnangagwa aimed to reassure voters, saying "government will do all in its power to ensure that the 2018 general elections, are credible, free and fair."

He is expected to appoint former head of the army Constantino Chiwenga as his vice president after he retired him this week "pending redeployment." Chiwenga took on near hero-status after he was instrumental in organizing the coup.

Mnangagwa also said he would fix Zimbabwe's suffering economy, which deteriorated severely under Mugabe's rule. Inflation at one point in 2008 hit 231 million per cent.

"My government is committed to open Zimbabwe up to investment," the 75-year-old leader said in his 30-minute address.

With high levels of unemployment and poverty many Zimbabweans have crossed the border to seek work in neighbouring South Africa.