"The charges dropped are insulting the president and causing disaffection to the armed forces," said Chris Mhike.
"The state is now only left with two charges, which is treason and making statements likely to cause public disorder," Mhike said, adding that they are going back to court on December 4.
The Movement for Democratic Change (MDC) number two was arrested on June 12 after arriving back in Zimbabwe following a lengthy stay in South Africa.
Biti could face the death penalty if convicted on the treason charge, which centres around claims he plotted to rig his party’s victory in the first round of Zimbabwe’s presidential election in March.
He was arrested during the run-up to the controversial June run-off election, and the MDC has maintained that the charges were part of a coordinated campaign of harassment and intimidation ahead of the polls.
MDC leader Morgan Tsvangirai pulled out the run-off citing violence against its members. President Robert Mugabe went on to contest the election unopposed, resulting in a widely condemned victory.
In September, the MDC signed a unity government accord with the ruling Mugabe’s ZANU-PF, but the deal remains stalled over a deadlock about how to share control of key cabinet posts. – AFP