Biti had been wanted by the authorities after proclaiming on March 30 that the MDC had won both the presidential and parliamentary elections before an official announcement was made.
He left the country soon after the disputed March 29 elections to seek African support for the MDC.
Nqobizitha Mlilo, a senior official of the MDC, told Al Jazeera on Thursday that it was not clear what charges will be brought against Biti.
He said the MDC's national spokesman, Nelson Chamisa, was in a position to shed light on the nature of charges Biti would face.
|"Whatever charges may be, the point remains that this is unnecessary harassment on the leadership of the MDC and the people of Zimbabwe"|
Mlilo, senior official of the MDC
Mlilo said: "Whatever charges may be, the point remains that this is unnecessary harassment on the leadership of the MDC and the people of Zimbabwe.
"What the people of Zimbabwe want is change and that change is represented by Mr Tindai Biti, Nelson Chamisa, Roy Bennett - the leadership of the MDC in general and president Tsvangirai.
"This is what the focus should be -- to give the people of Zimbabwe a new beginning and a new life.
"We have been very clear consistently since 2000 that we can never have free and fair elections in Zimbabwe.
"In fact, the socio-polical framework in Zimbabwe is incapable of producing a free and fair election ... What we demand is the will of the people of Zimbabwe to be respected and their will must be allowed to prevail."
The MDC and human rights groups have accused president Robert Mugabe's government of waging a violent intimidation campaign ahead of the run-off against MDC leader Morgan Tsvangirai.
The MDC says Zanu-PF activists have killed 66 opposition supporters to try to intimidate voters before the run-off, and police have detained Tsvangirai twice over the past week while he was attempting to campaign.
The ruling party blames the opposition for the political violence.
Tsvangirai beat Mugabe in the first round of elections in March but didn't get enough votes to avoid a run-off, according to official figures.
Mugabe's support has been eroded by the economic collapse of the once prosperous country, which he has ruled since independence from Britain in 1980.
Tsvangirai says Zimbabweans cannot afford Mugabe's rule any longer.