Negeri Sembilan Bersatu chief Rais Yatim said calls to curb deaths in custody must be heeded.

He said this in reference to the recent death of M Proosothaman who was a prisoner at Sungai Buloh prison.

"The deaths among prisoners is increasing. The latest incident is 26-year-old who died while under the custody of Sungai Buloh prison.

"The many voices (asking to address death in custody) must be heard... The condition in lockups such as medication, cleanliness, food, treatment and enforcers are still issues," Rais said in a Twitter posting.

Earlier today, Lawyers for Liberty called for an investigation into the death of Proosothaman, who died yesterday.

The NGO claimed Proosothaman was suffering from tuberculosis and was only sent to Sungai Buloh Hospital after he became unconscious.

Malaysian prisons are known to suffer poor conditions and activists who have been imprisoned have also complained about the appaling situation.