By Charles Haviland
BBC News, Kathmandu
Maoist rebels in southern Nepal have disrupted a meeting of the right-wing Hindu Shiv Sena organisation, resulting in a tense standoff between the groups.
Hindus form 80% of the Nepalese population
Shiv Sena members had gathered to protest against the removal of the country's Hindu status after 40 years.
The standoff was probably the first of its kind since parliament declared Nepal no longer a Hindu nation in May.
Nepal is at least 80% Hindu, but the religion is often closely intertwined with Buddhism or traditional faiths.
This was a confrontation between two groups at the opposite ends of the Nepalese political spectrum.
The move to make the country secular has outraged Hindu nationalist groups who have staged a number of protest gatherings in the capital and in southern towns near the Indian border.
Sunday's meeting in the town of Bhairahawa - near the birthplace of Lord Buddha - was disrupted by Maoists carrying black flags, who seized microphones and accused the gathering of being pro-monarchy.
They then blockaded roads and burned tyres.
In response, the chairman of the pro-Hindu organisers, Shiv Sena Nepal, warned they might start an armed religious movement to reinstate Nepal's Hindu status.
The most vocal opponents of secularism here are right-wing nationalist groups with close ties to their Indian equivalents.
Indeed, many demonstrators come in from India, where Hindu groups have declared Nepal's King Gyanendra to be the emperor of Hindus worldwide.
Many ordinary Nepalese Hindus also oppose the move to secularism, saying it is insulting and unnecessary. But religious and ethnic minorities have welcomed the change.