Maoist rebels in the Indian state of West Bengal have called off a month-old ceasefire.
A statement signed by Maoist leader Akash said they took the decision as the government had continued military operations against the rebels.
Hours later, rebels killed a worker of the governing Trinamul Congress party and his son, police officials said.
The rebels want the government to withdraw its forces from the Junglemahal area where they are active.
The rebels operate in several eastern and central states.
Soon after winning the state assembly elections in May, West Bengal Chief Minister Mamata Banerjee appointed a team of mediators to negotiate with the Maoists.
Starting peace talks with the rebels was part of her election manifesto.
The Maoists began a ceasefire on 3 October after a meeting with government-appointed mediators.
However, in the statement issued by rebels on Monday, Akash questioned the independence of the mediators and hinted that they were acting on behalf of the government.
Later in the day, rebels gunned down a Trinamul Congress worker and his son in Balarampur area of Purulia district, police said.
The BBC's Amitabh Bhattashali in Calcutta says the government has conducted a number of raids on rebel hideouts, and arrested two senior rebel leaders over the weekend.
The Junglemahal region of West Bengal, which borders the state of Jharkhand, comprises the restive West Midnapore, Bankura and Purulia districts.
In May 2010, more than 145 people were killed when a train crashed in the area after Maoist rebels allegedly sabotaged the rails.
The rebels say they are fighting for the rights of indigenous tribal people and the rural poor.
A government offensive against the rebels - widely referred to as Operation Green Hunt - began in late 2009.
It involves 50,000 paramilitary troops and is taking place across five states - West Bengal, Jharkhand, Bihar, Orissa and Chhattisgarh.