Madhesi protesters, on Wednesday, attacked vehicles escorting Nepal's president and hurled a petrol bomb at a temple that she visited.
Protesters from the Samyukta Loktantrik Madhesi Morcha intensified their protest against the new constitution by hurling stones at Nepal President Bidhya Devi Bhandari's motorcade as she visited Janakpur town on Wednesday.
The Madhesis were also reportedly angered by the president's visit to the Janaki Temple in the area, and hurled a petrol bomb after her visit which set a canopy in the temple premises on fire, The Kathmandu Post reported.
Indian ambassador Ranjit Rae, who was also scheduled to visit the temple, cancelled the plan following the incident, IANS reported.
The Nepali president was reportedly accompanied by General Rabindra Chhetri, the Chief of the Army Staff of Nepal Army.
At least 20 people were injured when the Nepali Police used tear gas shells on the Madhesi protesters, according to The Himalayan Times.
Bhandari, who represents the ruling CPN-UML party, was appointed the country's first woman president in October.
Madhesis have been protesting against the new Constitution brought in in September as it seeks to divide the country into seven provinces. The Madhesis are demanding changes in the splitting of federal provinces in the country and more representation in the government.
Violent protests have led to several deaths in recent months in Nepal, while the blockade at the India-Nepal border had led to shortages of essential goods in the Himalayan nation.