Zimbabwe's president has urged thousands of his supporters at a rally to deliver a "thunderous victory" in this month's national elections and proclaimed that "no one will stop us from ruling this country."

President Emmerson Mnangagwa said on Wednesday that people who vote for his ruling ZANU-PF party — which has been in power for 43 years — would go to heaven.

Mnangwagwa, the 80-year-old leader who assumed power in the southern African nation in a coup in 2017, also warned his supporters against engaging in violence in the run-up to the August 23 vote.

That plea came days after an opposition party supporter was killed, allegedly at the hands of ruling party activists, in the first deadly violence of the election buildup.

"Perpetrators of violence will be brought to book without fear or favour. So, I say to you, don’t ever perpetrate violence, we will deal with you," Mnangagwa said.

But while Mnangagwa has often called on his supporters to act peacefully, it hasn't spared the leader and his administration from criticism by international rights groups, including Amnesty International and Human Rights Watch.

They say that no matter what the president says, there has been a brutal crackdown on any opposition in Zimbabwe, and Mnangagwa and ZANU-PF are using institutions like the police and the courts to arrest critics, ban opposition rallies and stifle any challenge to their rule.

Main opposition leader Nelson Chamisa said in an interview with The Associated Press last week that Zimbabweans often face the threat of deadly violence if they don't support the ruling party.

ZANU-PF has been Zimbabwe's ruling party ever since independence from white minority rule in 1980.

'No one will stop us from ruling this country'

Supporters at Wednesday's rally received gifts of loaves of bread in plastic wrapping with Mnangagwa's face on them.

"We will forever march forward," Mnangagwa said at the rally in the capital, Harare.

"No one will stop us from ruling this country. We are the only party that brought independence and freedom to the colonised people of this country. We kicked out imperialism."

"So you will be lost if you don’t vote for ZANU-PF — you would have betrayed our freedom fighters. We need a thunderous victory to consolidate our hard-won independence," he added.

Zimbabwe has a history of violent elections, and although Mnangagwa told his supporters to act peacefully, he also blamed Zimbabwe's insecurity on "negative forces" outside the country, repeating the kind of rhetoric that former president Robert Mugabe used to blame the country's woes on others, most notably Western nations.

Zimbabwe is under US and European Union sanctions and has generally been shunned by the West for 20 years because of human rights abuses under the autocratic Mugabe, who died in 2019.

Mnangagwa replaced then ZANU-PF leader Mugabe in a coup in 2017 and won a close and disputed presidential election against Chamisa in 2018.

Chamisa will challenge Mnangagwa again for the presidency in this month's elections and has already made allegations of election manipulation.