US President Donald Trump on Monday extended by one year sanctions against Zimbabwe saying that the new government's policies continue to pose an "unusual and extraordinary" threat to US foreign policy.

The renewal comes despite calls by African leaders, including South Africa's President Cyril Ramaphosa, for the sanctions to be lifted to give the country a chance to recover from its economic crisis.

"The actions and policies of these persons continue to pose an unusual and extraordinary threat to the foreign policy of the United States," Trump said in a notice announcing the extension, adding: "I am continuing for (one) year the national emergency declared in Executive Order 13288."

The renewal comes despite calls by African leaders, including South Africa's President Cyril Ramaphosa, for the sanctions to be lifted to give the country a chance to recover from its economic crisis.

Trump administration officials had said the sanctions will remain until the government of President Emmerson Mnangagwa changes Zimbabwe's laws restricting media freedom and allowing protests.

According to US officials, there are 141 entities and individuals in Zimbabwe, including Mnangagwa and long-time former president Robert Mugabe, currently under US sanctions.

Mnangagwa has called for the sanctions to be lifted against the ZANU-PF ruling party, top military figures and some government-owned firms, which were imposed during Mugabe's rule over what the United States said were human rights violations and undermining of the democratic process.