The raids were carried out in Bulandshahr, Lucknow, Fatehpur, Azamgarh, Allahabad, Noida, Gorakhpur and Deoria.

Cases of illegal mining have been registered against Bulandshahr District Magistrate Abhay Kumar Singh and former Deoria District Magistrate Vivek among others.

The CBI has reportedly seized Rs 47 lakh cash from Abhay Kumar Singh's residence.

Cash amounting to Rs 10 lakh was found from the premises of Devi Sharan Upadhyay, a former Additional District Magistrate of Deoria (now posted as CDO, Azamgarh).

The CBI also seized property documents from the premises of Vivek, the former District Magistrate now posted as the Director of Training and Employment, Lucknow.

The development can spell trouble for former Uttar Pradesh Chief Minister Akhilesh Yadav since he has been linked to illegal mining.

Abhay Kumar Singh has been under the CBI scanner for alleged irregularities in mining when he was the District Magistrate of Fatehpur during the Akhilesh government.

Akhilesh Yadav was the Chief Minister of Uttar Pradesh from 2012 to 2017 and also the Mining Minister from 2012 to 2013.

The illegal mining allegedly took place between 2012 and 2016.

Sources in the CBI said that a total of 22 tenders passed by the UP government between 2012 and 2016 were being scrutinised.

Of these, 14 were passed when Akhilesh Yadav held the mining portfolio and the rest when Gayatri Prajapati was the Mining Minister.

Prajapati is presently in jail on charges of gang rape of a woman and her minor daughter. In June, the CBI searched his residence in Amethi.

The CBI had then conducted searches at 22 locations across the country, including at three premises of Prajapati in Amethi.

Earlier this year in January, the CBI raided several locations in Uttar Pradesh and Delhi in connection with the case.

The homes of senior officers, including IAS officer B. Chandrakala in Hamirpur, who served as the District Magistrate of Bijnor, Bulandshahr and Meerut, were searched by the CBI.

SP MLC Ramesh Misra and his brother, mining clerk Ram Ashray Prajapati, Ambika Tiwari from Hamirpur, mining clerk Ram Avatar Singh and his relative and Sanjay Dikshit were among the accused in the case.

According to the CBI, these officials allegedly allowed illegal mining in 2012-16.

"The accused and certain other persons illegally granted and renewed fresh leases and permitted obstructed period. These persons were allowed to extort money from leaseholders and also extract money from drivers carrying minerals," a CBI official said.

An FIR was registered after the Allahabad High Court directed the CBI to conduct inquiries over allegations of illegal sand mining in the five districts of Shamli, Hamirpur, Fatehpur, Siddhartha Nagar and Deoria.