The Indian Government has reiterated its opposition to discussing caste discrimination at a UN conference on racism later this month.
Authorities in Delhi said the caste issue is not the same as racism and that any discrimination on the basis of caste must be treated as an internal matter.
Discrimination by caste is outlawed in India but it is a part of daily life
But members of India's lowest caste disagree, saying the subject should be on the conference agenda.
Human rights activists have also criticised the government's decision.
Opinion is divided over the origins of the caste system, which dates back more than 3,000 years.
The degree to which it is a central tenet of Hinduism or the legacy of a power structure imposed by invaders from central Asia centuries ago is open to debate.
Higher caste members were traditionally associated with professions such as the priesthood, while those from lower castes were classed as servants; the lowest caste of all has traditionally been referred to as outcasts or untouchables.
Even so, the Indian Government has introduced a series of measures to give these people access to education and non-traditional jobs.
Discrimination by caste is outlawed in India but it is a part of daily life for the world's second most populous nation.
And, as indicated by the deaths of two teenage lovers who were hanged by fellow villagers earlier this month in the northern state of Uttar Pradesh for being from different castes, individuals ignore the system at their peril.
The caste system is rigidly observed across India
But the Indian Minister of State for External Affairs, Omar Abdullah, said on Thursday caste discrimination could not be equated with racism.
The minister rejected calls to discuss the caste system at the UN World Conference Against Racism due to be held in South Africa later this month.
That decision has angered the Dalits - the 160 million members of India's lowest caste.
Dalit representatives told reporters that India was failing to put its experience of racism and intolerance under international scrutiny.
The decision has also attracted criticism from the non-governmental organisation, Human Rights Watch.
Spokeswoman Smita Narula says caste-based discrimination is Asia's "hidden apartheid", which affects tens of millions of people across south Asia.