His former chief of staff said he could be away for up to 15 days.
After the coup, West African leaders said they wanted a rapid return to civilian rule. Mali's new military rulers had previously said they wanted the interim period to last for two years.
"We make a commitment before you to spare no effort in the implementation of all these resolutions in the exclusive interest of the Malian people," Col Assimi Goita, the head of Mali's military junta, said.
President Keïta was overthrown on 18 August following mass protests against his rule over corruption, the mismanagement of the economy and a dispute over legislative elections.
The coup sparked international condemnation, but it was welcomed by many Malians.
Mr Keïta was detained by the military, but later freed.
This was the fourth coup in the West African state since it gained independence from France in 1960.
A previous coup in 2012 led to militant Islamists exploiting the instability to seize territory in northern Mali. French troops helped regain territory, but attacks continue.
The coup leaders earlier promised to respect international agreements on fighting jihadists.
Thousands of French, African and UN troops are based in the country to tackle the militants. (BBC)