The move prompted Opposition parties to accuse the government of acting under pressure from the mining mafia. "What mistake has she made? It is felt she was suspended under the influence of the mafia," BJP's Kalraj Mishra said Sunday.
Chief minister Akhilesh Yadav tweeted in response: "It is an administrative decision."
Nagpal had lodged two dozen FIRs against the sand mafia and arrested more than a dozen people after forming a special team to curb rampant illegal mining in her district, especially along the Yamuna and Hindon rivers.
Only last week, the 2009-batch officer had asserted there would be no let-up in her fight.
"We had to shut our business for two months because of Nagpal's drive against sand mining in the Yamuna. We are happy with her suspension," said one mining contractor, requesting anonymity.
On Monday, the IAS officers' association in the state demanded that Nagpal's suspension be revoked. Opposition parties in the state criticised the Samajwadi Party government for "harassing" the officer.
Read: Sand mafia has the way in Noida