Underworld don Chhota Shakeel's aide and murder-accused Madoor Isubu, and his associate Ganesh Shetty were killed in a clash between two groups of inmates in Mangaluru jail on Monday.

At least 12 inmates and one policeman were also injured in the clash. They have been admitted to Wenlock hospital for treatment.

The clash broke out in the morning when the inmates had gathered for breakfast. According to a report in Daji World, Isubu and Shetty were killed with weapons whose nature has not been specified.

"It was a fight between two gangs and not a communal issue. One gang killed Madoor Isubu and his associate Ganesh Shetty, who were in the other gang. The fight took place during breakfast," said Mangaluru Police Commissioner S Murugan.

Commenting on the inmates' access to weapons, Murugan said accomplices of the culprits might have thrown it over the prison wall.

The reason behind the clash is unknown as of yet. The police have beefed up security in and around the jail and initiated an investigation.

Isubu, who was on the wanted list of the Dakshina Kannada District police since 2003, was arrested in Bengaluru in 2010. He had been lodged in Mangaluru jail since then. Isubu was wanted in more than 17 criminal cases, including four murders, attempt to murder, rioting and extortion.

Isubu's associate Shetty was a sharpshooter, and arrested in 2010 in connection with a killing in 1994.