Amid continuing protests against the Kudankulam Nuclear Power Project, Mr Udhayakumar's change of plans was announced by anti-corruption activist Arvind Kejriwal, who has extended his support for the anti-nuclear stir.
Mr Udhayakumar, convener of Peoples Movement Against Nuclear Energy, had yesterday said he would surrender before police at 9 PM last night but was whisked away in a boat by his emotional supporters who rejected his surrender offer.
"I met Udhayakumar in the morning and requested him not to surrender. He should use all legal remedies. It is extremely important that he remains outside and should not offer himself to police. He is convinced and he agreed," said Mr Kejriwal, who arrived at Idinthakarai last night.
Mr Kejriwal, a member of the disbanded Team Anna, also attacked the UPA at the Centre and Tamil Nadu Chief Minister Jayalalithaa for the police action against the protesters and "harassing" locals, who are up in arms against the project.
"Police should not harass and torture protesters, warning people would teach a lesson to Jayalalithaa in 2014 if it is not stopped," Mr Kejriwal said.
He said police should be more humane but he understood their constraints as they were acting under the instructions of the UPA at the Centre and Jayalalithaa government.
He said, "We need power but we also need to take people out of poverty. We need inclusive development."
The year-long stir had turned violent on Monday, with protesters engaging police in pitched battles that led to firing in which one person was killed besides lathicharge and bursting of teargas shells.
Meanwhile, police charged that PMANE was using people as shield and they were determined to arrest Udhayakumar.
As the relay fast continued at Idinthakarai, some advocates staged demonstrations demanding closure of the plant and blocked road traffic for more than an hour in Tirunelveli town.
With the protests spreading, fishermen at Pamban in Ramanthapuram district held a fast demanding closure of the plant and condemning the police firing.
Superintendent of Police Vijayendra Bidari accused Udhayakumar and his group of "spreading lies and rumours" to mobilise people and indulge in violence. He said steps had been intensified to arrest those responsible for the violence on Monday.
Police said more forces from Paramakudi had arrived.
The anti-nuclear protests, confined to Tirunelveli district where the plant is located, had spilled over to Tuticorin besides Chennai, Coimbatore and Erode.
The anti-KNPP stir was stepped up last week after authorities gave the go-ahead for loading uranium fuel into the plant. The Madras High court also gave clearance for commissioning of the Indo-Russian joint venture which has been bogged down by delays due to protests.