Zimbabwean former war veterans minister Tshinga Dube has reportedly described ex-president Robert Mugabe as a "bitter, senile old man", who was "absolutely intoxicated by power, hence his failure to accept that he was no longer president".

According to NewsDay, Dube said this after Mugabe last week told journalists at his mansion in Harare that President Emmerson Mnangagwa had been imposed by the army and was in office illegally.

Mugabe, 94, was forced to quit the political scene he had dominated since independence from Britain in 1980 when the military stepped in and Zanu-PF lawmakers launched impeachment proceedings against their once beloved leader.

Dube said that Mugabe should not be taken "seriously".

"When a very old man talks, we don’t worry, you forgive him, that’s why we say an old man has a right to say anything and we just say this is an elderly person. We don’t even have to answer. We don’t take him seriously.

"We are moving forward as you can see we are moving into a new era. We have been stagnant for more than 30 years because of him. We want to build the country and you can see things are beginning to move. So whatever he is saying we don’t worry about that," Dube was quoted as saying.

Mugabe indicated during his press briefing that he was ready for discussions to "undo this disgrace we have imposed on ourselves". But he maintained that Mnangagwa must invite him "properly" for the talks.

"I am willing to discuss and I am willing to assist in that process but I must be invited properly. Currently I am isolated," said Mugabe.

But presidential spokesperson George Charamba trashed Mugabe's claims, saying that it was absurd for the nonagenarian "to place himself above the entire State and polity, and arrogate power to bestow legitimacy".

Charamba urged Mugabe to approach the courts of law if he believed that Mnangagwa's administration was not legitimate.