Thousands of refugees in Nepal protested on the Indian frontier as border guards stopped them from crossing into India on their way to their birthplace in Bhutan.
The protests came after Bhutan held its second 'mock election' this week as a dress rehearsal for the kingdom's transition to democracy in 2008 after a century of royal rule.
The refugees have demanded their right to return to their birthplace to vote.
At least 35 policemen and dozens of refugees were injured on Monday and Tuesday as many of the estimated 10,000 refugees hurled stones at Indian forces, demanding passage to Bhutan.
"Bhutanese refugees are still continuing a sit-in demonstration on the bank of Mechi river on the Nepal side peacefully, amid huge deployment of border guards," Ravinder Jit Singh Nalwa, a top Indian police officer, said.
Tens of thousands of ethnic Nepalis were expelled from Himalayan Bhutan or fled in 1991 for demanding democracy and protesting against discrimination. About 106,000 live in impoverished conditions in crowded camps in southeastern Nepal.
India fears that allowing the refugees into the country could spark disturbances within its own borders. The refugees must cross West Bengal to reach Bhutan from Nepal.
Bhutan said it was not involved in the border stand-off.
"Right now, it is strictly an issue between India and Nepal and we have nothing to comment," a senior Bhutanese Foreign Ministry official told Reuters by phone from Thimphu.