Chairman of the Kerala Congress (B), an ally of the opposition Congress party, and member of the board of directors of the powerful Nair Service Society (NSS), Pillai surrendered before the special court for the Idamalayar dam corruption case which handed him over to the police.

Pillai, 75, arrived at the court with his film star son KB Ganesh Kumar, who is also a legislator of his party and a former minister, and son-in-law T Balakrishnan, the additional chief secretary of the state government.

The court located in the port city of Kochi had issued a non-bailable arrest warrant against Pillai on Wednesday while dismissing his plea to grant more time to surrender as he was planning to file a review petition before the apex court against its verdict.

He was sentenced by the trial court a decade back which was overruled by the High Court against which Chief Minister and senior Communist Party of India-Marxist (CPI-M) leader VS Achuthanandan went in appeal in the apex court and got it annulled.

The development is seen as a setback for the opposition ahead of the May elections to the assembly which it appeared set to win. Addressing a pre-poll rally in Kasaragod, Achuthanandan welcomed the imprisonment of his political adversary and said he was confident that all those indulging in corruption and exploitation of women would end up in jail.

One of the senior most politicians in Kerala, Pillai served as a legislator for several years together since the age of 25 in 1960 and has held ministerial portfolios like transport, electricity and irrigation since 1975. He served under C Achutha Menon, K Karunakaran, EK Nayanar and AK Antony.

He was sentenced under the Prevention of Corruption Act for causing a loss of Rs20mn to the exchequer as a leak appeared during the trial run on the newly-built tunnel and surge shaft in 1982 when he was the electricity minister in the Karunakaran ministry.

PK Sajeevan, a contractor who benefited from the flawed work contract, was also sent to jail along with Pillai. Both of them also paid a fine of Rs10,000.

However, the police could not serve the warrant on former Kerala State Electricity Board chairman Ramabhadran Nair, 82, as he is suffering from acute Alzheimer's disease and was bedridden for the past two years.

Before entering the courtroom, Pillai said he had full faith in the judiciary and he was a victim of a conspiracy by Achuthanandan. He was not allowed to speak to the press while in the custody of the police who took him by road to the Poojappura central prison some 220 km away in the state capital.

Earlier, his friends and followers, including megastar Mammootty, who is close to his son Ganesh Kumar, visited him in a city apartment where he was staying before surrendering in the court.

The Supreme Court had last week sentenced him along with Ramabhadran Nair, former chairman, KSEB and P.K. Sajeev, friend of Pillai, to one year rigorous imprisonment in the case, overturning the High Court verdict acquitting all the three.

Sajeev also surrendered along with Pillai and both of them remitted Rs 10,000 each as fines. City Police had made arrangement for crowd control at the court premises. P.M. Varghese, Assistant Commissioner of Police, Thrikkakkara, supervised the police deployed over there.

The case relates to awarding of contracts for the construction of a power tunnel and surge shaft of the Idamalayar project at exhorbitant rates to a now deceased contractor during UDF rule in 1980-87. The deal reportedly caused Rs 2 crore loss to the KSEB. Pillai was then Minister for Power.