Clashes have erupted in New Delhi between thousands of protesters and police, the latest violence in a week of opposition to a new law that makes it easier for non-Muslims from neighbouring countries to gain citizenship.

Key points: At least 100 people were wounded during the protests

At least 100 people were wounded during the protests Prime Minister Narendra Modi said his rivals were trying to incite students using 'guerilla politics'

Prime Minister Narendra Modi said his rivals were trying to incite students using 'guerilla politics' Pakistani Prime Minister Imran Khan said India's actions could create a refugee crisis

Prime Minister Narendra Modi's Government said the new law will save religious minorities such as Hindus and Christians from persecution in neighbouring Bangladesh, Pakistan and Afghanistan by offering them a path to Indian citizenship.

"This Act illustrates India's centuries-old culture of acceptance, harmony, compassion and brotherhood," Mr Modi tweeted on Monday.

But the law does not apply to Muslims, which critics say weakens India's secular foundations.

Police fired tear gas in the New Seelampur part of the capital to push back protesters swarming barricades and throwing stones. Many were injured, including two police officers.

Protests were also reported in the states of West Bengal, Kerala and Karnataka.

Cars were damaged and roads strewn with rocks while small fires on the road sent smoke into the air.

Multiple demonstrator were injured during clashes across India. ( Reuters: Sivaram V )

The metro train station near the Delhi protest was closed to prevent more people from arriving. Riot police were deployed and were trying to push the crowd off the main road into side streets and alleys.

Earlier this week, police officers entered Delhi's Jamia Millia Islamia university campus and fired tear gas to break up a protest. At least 100 people were wounded in the crackdown, which has drawn criticism from rights groups.

Police spokesman M.S. Randhawa said 10 people were arrested during Sunday's protest from Jamia Nagar, a Muslim neighbourhood near the university.

"We found out that the arrested men had instigated the crowds and were also responsible for vandalising the public property," Mr Randhawa said.

Students said police lobbed teargas shells inside the campus, broke down the doors of the library and yanked students out to assault them. Dozens of students were taken to local hospitals for treatment.

Indian students of the Jamia Millia Islamia University shout slogans during a protest in New Delhi. ( AP: Altaf Qadri )

Police have denied the charges and said they acted with restraint.

The most violent protests occurred initially in the north-eastern state of Assam, where mobs torched buildings and train stations, angry the law would help thousands of immigrants from Bangladesh become citizens.

'There could be a refugee crisis'

Mr Modi told a rally for a state election on Tuesday (local time) that his political rivals were trying to mislead students and others to stir up protests.

"This is guerrilla politics, they should stop doing this," he said.

There have been growing questions about the stance of the government, led by Mr Modi's Hindu-nationalist party, towards India's 172 million Muslims, which represents 14 per cent of the population.

The citizenship law follows the revocation of the special status of the Muslim-majority Kashmir region, and a court ruling clearing the way for the construction of a Hindu temple on the site of a mosque razed by Hindu zealots.

Pakistani Prime Minister Imran Khan said India's actions in Kashmir and on the citizenship law could drive Muslims from India and create a refugee crisis.

"We are worried there not only could be a refugee crisis, we are worried it could lead to a conflict between two nuclear-armed countries," Mr Khan told a Global Forum on Refugees in Geneva.

"Our country will not be able to accommodate more refugees," he added, urging the world to "step in now".

Police officers detain a demonstrator during a protest in Seelampur. ( Reuters: Danish Siddiqui )

Reuters/AP