The year's maize harvest is said to be the worst on record
Aid agencies in Zimbabwe have complained that they remain subject to tight government controls despite the lifting of a ban on food aid.
Hopes that the government meant well by lifting the ban "were dashed", Fambai Ngirande, a spokesman for Zimbabwean aid groups, told the BBC.
They have to submit information on their staffing, equipment and operations or risk being barred.
The government imposed the ban, saying aid was being used politically.
It was introduced ahead of a presidential election in June and lifted last week.
Aid agencies have always denied government charges that they were helping the opposition campaign.
Critics of President Robert Mugabe accuse his government of only distributing food aid to his supporters - they say the ban was to make this more effective.
Mr Ngirande told the BBC's Network Africa programme that government officials made repeated threats - to investigate aid agencies or strike them off the register - at a meeting on Monday to explain the conditions for lifting the ban.
He said police officers were present, and that all aid distribution would have to be done in conjunction with local officials.
An official from the Social Welfare ministry, Lancaster Museka, told the state-owned Herald newspaper that aid agencies would have to fill in forms detailing all the money they had received and how it had been used.
The form must also list where and when they have distributed food aid, he said.
The form must be signed by the agency's head, who can be prosecuted if any information is inaccurate, the Herald reports.
International aid agencies have broadly welcomed the end of the ban.
Agencies have warned that the maize harvest has been the worst on record and that by the end of the year, more than five million people - almost half the population - could be dependent on food aid.
Talks to resolve Zimbabwe's economic and political crisis remain deadlocked.
Mr Mugabe and opposition leader Morgan Tsvangirai are unable to agree on how to share power.
Both claim to have won this year's elections.