Raipur, July 20 (IANS) Maoists ambushed the convoy of Chhattisgarh Congress president Nandkumar Patel in a forested area in Raipur district Wednesday, police said. The Congress leader said seven party workers were killed, but police only confirmed four deaths, saying the figure could rise.

Additional Director General of Police Ramniwas confirmed four deaths, saying the figure could rise as five Congressmen were battling for life.

Local TV channels aired footage of a heavily damaged vehicle of the convoy which, officials at the police headquarters here said was tossed up several feet in the air. A senior official said that Maoists had probably mistaken the vehicle for a police vehicle and had blown it up.

There were an estimated 25 vehicles in the convoy and the vehicle that was ripped through was packed with Congress workers. It was at the rear end of the convoy.

"At least seven workers of my party were killed and four of them severely injured in the attack," Patel told IANS over phone in a choked voice. The attack site is about 150 km from Raipur.

"I am horrified by the attack, we were left at the mercy of Maoists in a jungle where police knew Maoists have developed massive presence in recent months," he said.

"There was a zero security to us despite Congress has informed the ruling Bharatiya Janata Party (BJP) government several days in advance about the programme of a farmers rally in the Mainpur-Devbhog area close to the Orissa border".

After the blast, Patel and his senior party colleagues were kept under security cover at Mainpur police station.

Congress leader and former minister Satyanarayan Sharma, who was in the convoy, said when the attack took place, Patel, (former state president) Dhanendra Sahu and other key leaders of the state unit of the party had safely moved out from the area.

Officials at the police headquarters said that a team of policemen had left from the Mainpur police station for the attack site to assess the situation.

The attack site is in the same area where Maoists had killed nine policemen, including Additional Superintendent of Police Rajesh Pawar, in an ambush in May.