Four aides to Zimbabwe's Prime Minister Morgan Tsvangirai were on Tuesday charged with breaching the official secrets code, impersonating the police and illegal possession of documents for criminal use.
Thabani Mpofu, director for research in Tsvangirai's office, two subordinates and a senior party official were arrested on Sunday, in the wake of a key constitutional referendum.
Their lawyer Beatrice Mtetwa was also detained in the raid on Tsvangirai's communications office, but faces separate charges.
Applying for bail, lawyer Alec Muchadehama complained that the four were arrested and detained unlawfully.
"These are good citizens who deserve not to stay in custody."
Prosecutor Michael Mugabe opposed bail saying the four were facing serious charges.
The arrests marred Zimbabwe's largely peaceful constitutional referendum, which took place on Saturday.
The vote is expected to handily approve a draft charter, which curtails the president's powers and reduces the president's tenure to two five-year terms.
Tsvangirai is in an uncomfortable coalition government with his arch-rival and veteran leader President Robert Mugabe, which will end with elections planned under the new constitution.
Zimbabwean police have launched a series of raids to seize two-way and shortwave radio receivers, a policy that rights groups say is a fig-leaf for intelligence gathering and intimidation.