The death of a woman allegedly due to physical assault by security personnel in Nalbari district, Assam, has provoked widespread protests, with the United Liberation Front of Asom calling a bandh on Tuesday and the All Assam Students Union moving the Assam Human Rights Commission on the issue.

Sabitri Rajbongsi (60), the mother of ULFA militant Bhaskar Rajbongsi, died on Saturday after being allegedly hit with rifle butts when she tried to protect her daughter-in-law from Central Reserve Police Force men looking for her son at Naomati.

With the administration in Nalbari district instituting a magisterial inquiry into the incident, Chief Minister Tarun Gogoi said Lower Assam's Division Commissioner J S L Vashava will probe the woman's death.

Protesting the attack on the elderly woman, the outlawed ULFA called a dawn-to-dusk bandh in Nalbari, affecting normal life in district and parts of Baksa district.

Markets, shops, educational institutions, banks and offices remained closed in these areas and vehicles stayed off the roads, officials said.

No untoward incident was reported from these areas.

Chief Minister Gogoi said: "Though there is an allegation that the woman died due to physical assault by security personnel, we have information she died of a heart attack."

The influential AASU has moved the Assam Human Rights Commission on the issue and have decided to observe Wednesday as a black day.

The Nalbari unit of the Asom Jatiyatabadi Yuba Chatra Parishad has formed a legal cell to assist Sabitri's family.