Indian Railway Minister Mamata Banerji has addressed a huge rally - supported by Maoists - at a rebel stronghold in West Bengal.
A senior Maoist leader had urged local people to attend the event in Lalgarh and thousands showed up.
Analsyts say Ms Banerji's appearance at the rally will embarrass the Congress Party-led federal government.
The Maoists were blamed for sabotaging and derailing an express train which killed nearly 150 passengers in May.
Ms Banerji and her Trinamul Congress Party, a Congress ally, have always denied any links with the insurgents.
The eastern Indian state of West Bengal is one of 20 where the rebels have a presence.
Prime Minister Manmohan Singh has described the Maoist insurgency as India's biggest internal security challenge.
At Monday's rally in Lalgarh, Ms Banerji called for negotiations between the Maoists and the government.
"I am against all kinds of terror. Terror should stop in Lalgarh and all areas around it and the counter-insurgency operations in the area should be stopped," she told flag-waving supporters.
Security forces and police have been conducting a huge counter-insurgency campaign against the rebels in the area.
A BBC correspondent in Lalgarh, Amitabh Bhattasali, says more than 10,000 rebel supporters converged in the area to back the rally.
Earlier, the police had said they would arrest any Maoist leader who attended.
But there have been no arrests, our correspondent says.