By Rina Chandran

MUMBAI (Thomson Reuters Foundation) - Members of India's low-caste Dalit community in Gujarat state have pledged to boycott the dirty jobs traditionally thrust upon them in protest over their treatment by upper-caste Hindus, said activists for the marginalized group.

Thousands of Dalits rallied on Sunday in the state capital Ahmedabad, blocking roads and attacking buses, local media reported.

Unrest in the state erupted last month after four Dalit men in the city of Una were tied to a car, stripped and flogged by Hindu vigilantes, who accused them of skinning a cow, a revered animal for Hindus.

"I urge all Dalits to discontinue the work of disposing dead animals ... (and) take a pledge of discontinuing the work of cleaning sewers," Jagdish Mevani, of a local Dalit rights group in Una, said at the rally.

"We no longer wish to do this work and want the government to allot agricultural land to us, so we can live a respectable life," he was quoted as saying by the Indian Express newspaper.

Landless Dalits are at the bottom of India's age-old social hierarchy, making them vulnerable to discrimination and attacks by upper-caste Hindus, including by hardline "gau rakshak" vigilantes who regard cows as sacred.

The slaughter of cows is banned in most Indian states including Gujarat, the home state of Prime Minister Narendra Modi. Dalits in the state have said they earn a livelihood from skinning cows and buffalos that die naturally.

The vigilantes chase trucks transporting cattle and raid slaughter houses. Several people accused of eating beef have also been attacked, including a Muslim man who was beaten to death last year by a mob in a town near New Delhi.

"What we observe in Gujarat is a measured outbreak against decades of impunity Dalits have suffered," said Paul Divakar, general secretary at the National Campaign on Dalit Human Rights.

"One cannot force unclean occupations on Dalits for centuries and then abuse and assault them for doing those very occupations," he told the Thomson Reuters Foundation.

Opposition parties have criticized the government for its handling of the protests, and Gujarat Chief Minister Anandiben Patel on Monday said she would resign from her post.

Caste-based discrimination was banned in India in 1955, but centuries-old attitudes persist and low-caste Indians still face prejudice in every sector, particularly in rural areas.

Crimes against India's lower-caste communities rose by almost a fifth to 47,064 in 2014 from the previous year, according to national data.

In Gujarat, crimes against lower-caste communities, including indigenous people, had a conviction rate about six times lower than the national average, according to IndiaSpend, which analysed data over a 10-year period.

India has passed several laws to end manual scavenging - a euphemism for disposing of faeces from dry toilets and open drains by hand - which has long been a task carried out mostly Dalit women.

Yet Dalit communities continue to face threats of violence, eviction and withholding of wages if they try to give up the practice, human rights groups say.

(Reporting by Rina Chandran @rinachandran, Editing by Ros Russell. Please credit the Thomson Reuters Foundation, the charitable arm of Thomson Reuters, that covers humanitarian news, women's rights, trafficking, corruption and climate change. Visit news.trust.org to see more stories.)