Chennai, April 5: Former Tamil Nadu agriculture minister S.S. Krishnamoorthy was arrested last night by his own government's police weeks after being sacked over charges that his men had driven an agriculture department engineer to suicide.

S. Muthukumarasamy, 57, had thrown himself before a train near Tirunelveli, 500km from here, on February 20 following alleged pressure by "Agri" Krishnamoorthy's staff to collect bribes from contract drivers he had recruited on merit.

As the engineer's colleagues agitated and the Opposition called for Krishnamoorthy's head and a CBI probe, the state's AIADMK government handed the case over to the crime branch.

Krishnamoorthy, a powerful party district secretary, was stripped of that post and later dropped from the ministry last month.

Muthukumarasamy was known for his honesty and was to retire later this year, a police officer said.

The crime branch yesterday summoned Krishnamoorthy for questioning following the interrogation of an arrested chief engineer, and later arrested him. He was today driven to Tirunelveli, where a magistrate sent him to 15 days' judicial custody.

Tirunelveli collector M. Karunakaran had been quoted as saying that Muthukumarasamy had told him he was under severe pressure to change the list of appointees or extract bribes from them and send the money to the then minister's office.

"Apparently, the (then) minister's staff had collected bribes against promised appointments but Muthukumarasamy went by the book and took the list of qualified candidates from the employment exchange," a police officer said.

"The corrupt officials were under pressure to return the bribe money. So they asked him to come up with the money and threatened to have him suspended if he didn't."

The sacking and arrest of Krishnamoorthy bore the political fingerprints of Jayalalithaa, unseated as chief minister last September following her conviction in an assets case, party sources said.

Such action against her own former minister suggests she is trying to spruce the image of a state government buffeted by several scandals.

A sceptical Opposition termed the arrest a "cover-up" and an "eyewash". The DMK, Congress, BJP, Left and the PMK stood united in insisting that only a CBI probe would satisfy them, a PTI report said.

Jayalaithaa's party sources said the arrest indicated she might be gearing to call snap polls before December.

"A few more ministers (facing corruption allegations) may lose their posts in a pre-election purge," a senior party official said.

Jayalalithaa is awaiting the outcome of her appeal before Karnataka High Court against her conviction, which makes her ineligible to contest elections for the four years of her jail term plus another six years. She is out on bail after spending three weeks in a Bangalore jail. Muthukumarasamy, a soft-spoken assistant executive engineer, was posted in Tirunelveli where he supervised the construction and repair of irrigation canals and bunds.

"He was so honest he wouldn't attend even the contractor's family events," a colleague recalled.

Muthukumarasamy was part of a three-member committee, which included the collector and a motor vehicles inspector, that recruited temporary drivers on contract for the agriculture department.

As department representative, the engineer had signed the final list of seven candidates before the collector sent out the appointment letters.

Muthukumarasamy is survived by his wife and two sons, who work with IT companies in Chennai. "He was looking forward to his retirement so he could get us married and play with his grandchildren," son Sethuraman said.

"Agri" Krishnamoorthy had graduated from the agriculture university in Coimbatore and headed his party's agriculture wing.

He was appointed food minister in May 2011 and later moved to education before being dropped in 2012 in Jayalalithaa's habitual game of musical chairs. He was made agriculture minister in 2013.