Sonia Gandhi has expressed her anguish at the death of head constable Ratan Lal (File)
Congress president Sonia Gandhi has appealed to the people of Delhi to maintain communal harmony and defeat the powers that are trying to divide the nation on the basis of religion, the Congress said in a statement.
At least five people, including a police constable, were killed on Monday after violence broke out across northeast Delhi for a second time in less than 24 hours.
Protesters for and against the controversial citizenship law threw stones, set vehicles and shops ablaze and transformed parts of the national capital into a war zone, forcing the deployment of paramilitary forces and the banning of large gatherings in affected areas.
"In a statement Mrs Gandhi has expressed her anguish at the death of head constable Ratan Lal, who was killed in the violence, and has offered her condolences to his bereaved family," the statement in Hindi read.
"She has appealed to the people of the country that violence has no place in the India of Mahatma Gandhi, and powers that want to impose their communal and divisive ideology on the country have no place here," it added.
Senior Congress leader Rahul Gandhi has called the violence "disturbing".
"The violence today in Delhi is disturbing and must be unequivocally condemned. Peaceful protests are a sign of a healthy democracy, but violence can never be justified. I urge the citizens of Delhi to show restraint, compassion and understanding no matter what the provocation," he tweeted.
Congress general secretary Priyanka Gandhi Vadra has also urged the people of Delhi to maintain communal harmony.
"The day in Delhi was full of violence. Only common people face the brunt of violence. It is our responsibility to stop this. Mahatma Gandhi's country is the country of peace. I want to appeal to the people of Delhi to maintain peace, and I urge Congress workers to help maintain peace and harmony," she tweeted in Hindi.
In the evening, Union Home Secretary Ajay Bhalla said the situation was "under control" but violence continues to be reported from neighbourhoods in the area. The Union Home Ministry has said it will "monitor the situation".