Kerala Congress chief MM Hassan on Wednesday urged Chief Minister Pinarayi Vijayan to set up a special investigation team (SIT) to probe the killing of Youth Congress worker Shuhaib by suspected CPI (M) men in Kannur.

Hassan told the media in Thiruvananthapuram that it was most unfortunate that even after 36 hours of the brutal murder, police had no clues about what happened that day and no one had been taken into custody.

"This is the 21st political murder since the Vijayan government assumed office in May 2016. It appears the hands of police are tied... They are unable to go forward with an impartial probe.

"Apart from constituting an SIT, the provisions of Unlawful Activities (Prevention) Act should also be invoked against the perpetrators," said Hassan.

Thirty-year-old Shuhaib was found murdered on Monday night. The Kannur Congress unit blamed CPI (M) activists though the CPI (M) leadership has denied any link with the killing.

According to the party, Shoaib, along with a few others, was waiting in front of an eatery near Mattanoor around 10.45 pm on Monday when four persons came in a car and threw bombs to create a scare. They then slashed him with a sword.

On Wednesday, the Congress launched a 24-hour protest in Kannur in which top party leaders took part.

"Vijayan should speak up and condemn this heinous act... But he is not doing it because he is aware of what lies in store," alleged party's state vice president and senior legislator VD Satheesan, while inaugurating the protest.

Shoaib's father Mohammed told the media that his son was facing threats from the Communist Party of India-Marxist for a while and had recently been implicated in a false case by police and jailed.

The police have reportedly taken a CPI (M) worker into custody and are questioning him.