By Grant Ferrett
The New York-based group, Human Rights Watch, has accused the Zimbabwean Government of denying its opponents access to food supplies.
Some 3.8m Zimbabweans need food aid
In a report entitled "The Politicisation of Food in Zimbabwe," the group says farmers recently resettled as part of President Robert Mugabe's land redistribution policy are among those affected.
The government in Harare has denied the allegations.
An estimated five million Zimbabweans - more than a third of the population - will need food aid by the end of the year.
In its 50-page report, Human Rights Watch documents how those suspected of being opposition supporters are denied help.
'Serious as torture'
It says government and ruling Zanu-PF party officials manipulate the distribution of subsidised grain and the registration of those eligible for international food aid.
It describes the denial of access to food as a human rights violation as serious as arbitrary imprisonment or torture.
The ruling party's information secretary, Nathan Shamuyarira, categorically rejected the findings.
"There are so many people as you know in both London and Washington who write false reports about Zimbabwe. I can assure you that there is no politicisation of food."
The allegations of political interference in the distribution of food are not new, but the suggestion that small-scale farmers who have been resettled are also affected is more unusual.
Human Rights Watch says the Zimbabwean Government does not want to acknowledge that its highly controversial programme is a failure, and international relief agencies are complicit in preventing food from reaching the resettled farms.
The World Food Programme has denied the charge, saying it is still assessing the need in the resettled areas.
The repeated accusations of political bias in food distribution in Zimbabwe have hampered the UN's fund-raising efforts to tackle food shortages throughout southern Africa.
An appeal for more than $300m has so far produced promises from donors of little more than a $100m.