Raipur, Jul 21 (IANS): The Congress Thursday sought president's rule in Chhattisgarh citing a security breakdown under the Bharatiya Janata Party (BJP) government, a day after four party activists were killed and many injured in an attack by Maoists.

"The state is reeling under deadly attacks one after another. Wednesday's attack is a complete security breakdown in Chhattisgarh, the state should be placed under president's rule," Ajit Jogi, former chief minister and senior Congress leader, said in a statement.

The rebels had ambushed a vehicle, part of a 25-vehicle convoy led by Chhattisgarh Congress president Nandkumar Patel, in a forested area of Raipur district Wednesday evening. The attack took place some 150 km from state capital Raipur.

Jogi termed the attack on Patel's convoy an act of cowardice and said, "Maoist violence is at an all-time high in the state because of the BJP government's inability and inefficiency."

Patel claimed he was the main target of the attack and thanked god he escaped unhurt.

"I am horrified by the attack, we (Congress leaders) were left at the mercy of Maoists in a jungle where police knew Maoists have developed a massive presence in recent months," Patel told IANS.

"There was zero security to us despite the Congress informing (the state government) several days in advance about its programme of a farmers' rally in the Mainpur-Devbhog area close to the Orissa border."

Dozens of Congress workers staged demonstrations Thursday on the streets of Raipur amid heavy rain after five seriously injured party workers were shifted to a government hospital here in a critical condition.