In her latest missive to Singh, the Uttar Pradesh Chief Minister contended there has been an increase in the population of these communities but the quota has remained static, making it difficult to provide facilities to them.
Mayawati also stressed that OBCs should be included in the SC/ST list only after increasing the overall quota as per their population.
With Assembly elections in Uttar Pradesh due in another six months, she requested the Prime Minister to take a decision on the matter at the earliest.
Mayawati accused the Centre of showing little interest in implementing welfare schemes for these sections at the national level.
The Chief Minister has written about half a dozen letters to the Prime Minister in the last fortnight over various issues, mostly pertaining to the weaker sections, apparently with an eye on the upcoming polls.