Biti, a lawyer, said he had held a two hour meeting with President Mugabe and he had slept during most of it.
"I met with President Mugabe two weeks ago and he slept most of the time during the two and a half hour meeting," Biti told a rally in Kuwadzana.
"Most of the leaders he was with are now gone. A person born in 1980 is now about 31 years old. Samora Machel, Joachin Chissano and Nelson Mandela are gone.
He is tired and must go now too."Biti said most Zanu PF leaders were also tired and should leave office to pave way for a "younger generation of leaders".
Meanwhile, the Zanu PF controlled Zimbabwe Broadcasting Corporation (ZBC) has launched a President Robert Mugabe daily radio programme.
Introducing the programme which is going to run on Radio Zimbabwe (formerly Radio 2) radio presenters Elsie Majapelo and Perfect Thlongwane said the programme will be called Zvirongwa and will be broadcast every day profiling Mugabe’s ‘national development utterances’.
“This programme is going to bring the President closer to the people so that they appreciate him. This week we are going to review his Mutare statement which he made during the party’s conference which ended at the weekend, “said the presenters on Wednesday.
ZBC has been criticised for being biased towards Zanu (PF) party at the expense of the two Movement for Democratic Change (MDC) factions led by Morgan Tsvangirai and Arthur Mutambara who are also part of the unity government formed in 2009.
This year the ZBC authorised the playing of Zanu (PF) party jingles which denounce MDC.