Demonstrations have been held in Nepal for a fifth consecutive day after the vice-president spoke in Hindi at his swearing-in ceremony.
Protesters in Kathmandu demanded that Paramananda Jha publicly apologise for not using the official language of government, Nepali.
He says Hindi, which is widely used in Nepal, should be an official language.
Some analysts say the protests indicate anti-Hindi or anti-India sentiments common in Nepal.
On Monday, as student groups burned tyres and blocked traffic, the Supreme Court ordered that Mr Jha had five days to justify his actions after a lawsuit was filed against him last week.
Its backers argue that Mr Jha's oath should be invalidated because it must be carried out in Nepali.
"The vice president must retake the oath in Nepali or step down," the demonstrators chanted.
During the oath-taking ceremony last Wednesday, President Ram Baran Yadav, took the oath of office in the Nepali language from Chief Justice Kedar Prasad Giri.
But when his turn came, Mr Jha conducted his oath in Hindi.
Anti-India sentiments
"I translated the oath into Hindi so as to convenience the people of southern Nepal, who speak such languages as Maithili, Bhojpuri and Awadi. And Hindi is considered as our medium language," he told the BBC.
Nepal is a multi-ethnic, multi-lingual country, with nearly 100 different ethnic groups and as many languages.
But the use of Hindi, the official language of India, can be controversial.
The BBC's Surendra Phuyal in Kathmandu says that often Nepal's giant and influential neighbour is criticised in political circles for what has been described as "constant and unwanted meddling in Nepal's internal affairs".
The president and vice president were elected last weekend after a bitter contest between Nepal's political parties, including former Maoist rebels.
The constituent assembly elected in April declared Nepal as a republic, paving the way for the abolition of the 250-year-old monarchy.
^ Back to top | BBC Sport Home | BBC Homepage | Contact us | Help | ©
~RS~q~RS~~RS~z~RS~57~RS~)