The protests that flared up in Bihar ever since the Delhi government decided to make identity proof for any citizen living in the Capital mandatory from January 15, have gained momentum.

After the ruling Janata Dal-United and Bharatiya Janata Party leaders criticised the move, chief minister Nitish Kumar has sent a strongly-worded letter to Prime Minister Manmohan Singh [Images] against the decision of Delhi government.

"There is a growing tendency to ridicule Biharis among the higher-ups in Delhi. The whole exercise appears to be one such sinister design to target the people of Bihari origin," Nitish Kumar said in his four-page letter to the prime minister over the issue.

Kumar made it clear that nobody can claim jurisdiction over Delhi and that the contributions of the people of Bihar towards the development of Delhi cannot be ignored.

Bihar's former chief minister and senior JD-U leader Jagannath Mishra has urged Singh to intervene to resolve the issue which, he says, was a violation of the fundamental rights of Indian citizens.

Delhi lieutenant governor Tejinder Khanna said the decision to verify the identity of citizens has been taken to step up security in the Capital in the wake of recent terror attacks in various parts of the country.

Interestingly, UPA ally the Rashtriya Janata Dal is yet to react to the issue.