A team of National Investigation Agency (NIA) will today begin its probe into the Chhattisgarh Maoist attack on Congress leaders which claimed 28 lives including PCC Chief Nand Kumar Patel.

Speaking to reporters in New Delhi, Union Home Secretary R K Singh said an official order formally handing over the case to NIA to carry out the investigation would be issued soon. He also said, the NIA team will leave for Chhattisgarh today.

Home Minister Sushilkumar Shinde had earlier said the NIA will probe the Maoist attack on Congress leaders and the Centre has received a go-ahead from Chhattisgarh Chief Minister Raman Singh for it.

Mr. Shinde had also briefed Prime Minister Manmohan Singh about the decision to hand over the investigation to NIA.

Heavily-armed Maoists had on Saturday ambushed a convoy of Congress leaders in the state's Bastar district, killing 28 people including PCC chief Patel, his son Dinesh, Congress leader Mahendra Karma and ex-MLA Uday Mudliyar and injuring 32 others.

Union Minister V C Shukla injured in the attack is being treated at a Medanta hospital in Gurgaon, his condition is stated to be critical but stable.