Tamil Nadu was hit by protests for a fourth day on Wednesday to denounce the Centre's failure to set up a Cauvery Management Board (CMB), with demonstrators blocking rail lines and roads, witnesses and officials said.

In Chennai, DMK activists attempted lay siege to Chennai Metro Rail at Koyambedu but were taken into custody. Other protesters tried to block suburban trains in Perambur.

Demonstrators also squatted on a highway linking Chennai and Chengalpattu shouting slogans against the Central and Tamil Nadu governments, severely affecting traffic.

The DMK and its allies have called a state-wide shutdown on Thursday. They have also threatened to show black flags to Prime Minister Narendra Modi if and when he visits Tamil Nadu.

At Basin Bridge near here, members of the Communist Party of India blocked suburban trains. Similar protests took place in Madurai, Tirunelvelli and Thanjavur.

DMK MLA J. Anbazhagan launched a hunger strike over the Cauvery issue.

Meanwhile, DMK leader M.K. Stalin told reporters that leaders of the ruling AIADMK were pretending to be asleep and so it was not possible to wake them up.

Stalin said an all-party meeting would be convened on Thursday to decide on who all will march from Cauvery Delta region to Raj Bhavan here.

Meanwhile, actor-turned-politician Kamal Haasan, President of Makkal Needhi Maiam (MNM) party, accused the Modi government of delaying setting up a CMB in order to appease Karnataka, which is opposed to the Board and where Assembly elections are due.

The Supreme Court on February 16 reduced Tamil Nadu's share of Cauvery water from 177.25 thousand million cubic feet (TMC), which was less than the 192 TMC allocated by a tribunal in 2007. Karnataka's share of water was increased by 14.75 TMC.

The Centre failed to set up the CMB within six weeks of the apex court's February 16 order. The deadline ended on March 29.