Intervening in the matter, the National Commission for Scheduled Castes stated that it would carry out an investigation into the matter, while the state SC/ST Commission registered a case in this regard.
Akhila (30) and Anjana (25), daughters of Indian National Trade Union Congress leader N Rajan were summoned to the police station on Friday, where a case was registered against them.
They were then sent to the women's jail after being charged with non-bailable offences.
Akhila went to the jail with her one-and-half-year old daughter, family sources said.
After their release, the sisters were given a rousing reception by Congress activists.
"We do not know why the non-bailable charges were slapped against us. We had entered the CPI-M office, but did not attack anyone," Akhila said.
According to the police, the arrest was made on a complaint by the CPI-M that the women had barged into their party office and attacked one M Shijin, a party activist, some days ago.
However, Rajan, their father, rejected the charges and said the case was "politically motivated."
Rajan, who had contested in the last local body elections against a CPI-M candidate, also said Shijin had mocked his daughters calling them by their caste name when they were passing by in front of the party office and the girls had just questioned the verbal abuse.
"CPI-M activists manhandled my daughters when they entered the party office," he said, adding that the party workers even attacked their house the same day.
The first class magistrate court granted bail to the siblings and asked them to surrender their passports, if they had any.
Meanwhile, the National Commission for Scheduled Castes Chairman P L Punia said it would intervene in the matter and take steps to ensure that justice was meted out to them.
"We will intervene and inquire into the matter and ensure that justice is done to them ," he told a Malayalam news channel in New Delhi when asked about the issue.
The state Commission for Scheduled Castes and Scheduled Tribes offered free legal aid for the siblings to fight the case.
Meanwhile, DGP Loknath Behera has sought a report from ADGP North Zone on the matter immediately.
Chief Minister Pinarayi Vijayan, who is in New Delhi, told reporters that the matter had not come up before him and he would look into it.
Quick to react, opposition leader Ramesh Chennithala, who visited the women in jail earlier in the day, said the CM's response that he was unaware of the incident, was "unfortunate".
The Congress leader also said that the family was getting threats allegedly from CPI-M activists and wanted the chief minister's immediate intervention in the matter.
Former Chief Minister Oommen Chandy also attacked the LDF government and said police had violated all the guidelines and directions of the Supreme Court in the arrest of the Dalit women.
He also sought a comprehensive probe into the matter and demanded action against the officials responsible for the incident.
In a scathing attack against the LDF government, the BJP said the incident was a shame on the state's cultural society.
"The incident of abusing the Dalit women by calling them by the caste name and later registering a fake case against them was the latest example of the Pinarayi government's inhumane actions," BJP spokesperson J R Padmakumar said.
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