Ethiopia’s government has been withholding foreign aid from opposition supporters, Human Rights Watch says. Its report urged donors to ensure their aid was distributed transparently.
Ethiopia is one of the world’s largest recipient of development aid - in 2008 international donations to the country totalled $3bn (£1.8bn).
Its government has not yet commented on the report but has rejected similar accusations in the past as “ridiculous and outrageous”.
Human Rights Watch says its findings are based on a six-month investigation last year.
“We visited 53 villages in 26 districts in three regions of Ethiopia and we talked to about 200 people,” Human Rights Watch researcher Ben Rawlence told the BBC’s Network Africa programme.
“We found systematic discrimination from one end of the country to another against people who were members of the opposition party or people who disagreed with the regime.”
Villagers, who are often subsistence farmers, were rejected for micro-credit loans, seeds, fertiliser, food aid, housing if they were a member of an opposition party, he said.
“University places are conditional on ruling party membership, promotion in the civil service - if you’re a teacher or a nurse or a bureaucrat in a government ministry - all of these things are conditional on loyalty,” Mr Rawlence said.
“People are being asked to disassociate themselves from political parties - rescind comments they’ve made and write out letters of regret - in order to obtain food aid.”
Efforts to confirm the stories of discrimination with regional officials, civil society, opposition leaders and journalists revealed that this was how things commonly operated, he said.
The group says many donor officials privately acknowledge there is a deteriorating human rights situation and growing authoritarian rule.
At the same time it is generally accepted that Ethiopia is making impressive progress as it tries to develop.
BBC East Africa correspondent Will Ross says this leaves donors in a dilemma because they are reluctant to turn off the taps as they feel this would reverse the gains.