The National Investigation Agency (NIA) will probe the Maoist attack on Congress leaders in Chhattisgarh. Union Home Minister Sushilkumar Shinde told a news agency over phone from New York that he had spoken to Raman Singh and he has agreed for probe by the central agency.Shinde said he has asked Union Home Secretary R K Singh to proceed accordingly in the matter.

Shinde said he has briefed Prime Minister Manmohan Singh about the decision to hand over the investigation to NIA.

Heavily-armed Maoists had ambushed a convoy of Congress leaders in Chhattisgarh's Bastar district on Saturday, killing 28 people including Congress leader Mahendra Karma, Pradesh Congress Committee chief Nand Kumar Patel, his son Dinesh and ex-MLA Uday Mudliyar and injuring 32 others, including former union minister V C Shukla.Shukla is being treated at a Gurgaon base hospital where he is stated to be critical but stable.

Prime Minister Manmohan Singh and UPA chief Sonia Gandhi, Bharatiya Janata Party leader LK Advani and Delhi Chief Minister Sheila Dikshit visited the injured leader in hospital.

Earlier Mrs. Gandhi, Dr.Singh andCongress Vice president Rahul Gandhi had visited Chattisgarh to review the situation yesterday.

The Maoists attacked the Congress party convoy at around 5.15 pm on Saturday. The convoy, returning from the party's Parivartan Yatra was targeted near Darbha forest in Jagdalpur, about 340 km south of state capital Raipur.

Chhattisgarh is headed for Assembly Elections later this year.