Australian environmental activist Natalie Lowrey is still in the police lock-up while authorities decide whether to charge her.

“We are still handling this with the deputy public prosecutor,” said Kuantan OCPD Abdul Aziz Salleh, when asked if charges would be brought against her.

Lowrey ( right ) is among a group of 16 anti-Lynas protesters arrested on Sunday, but is the only one to be denied police bail due to her foreign citizenship.

Earlier, human rights NGO Suaram had questioned why the police failed to arrest "thugs" who allegedly attacked a group of activists outside the Kuantan police district headquarters yesterday.

The group had gathered in solidarity for the 16 who were arrested for protesting outside the Lynas Advance Material Plant in Gebeng, near Kuantan yesterday.

Suaram coordinator R Thevarajan strongly questioned why there was no similarly immediate police action to stop the supposed "violent attacks" by thugs that took place under their watchful eyes.

"Why was not a single thug arrested for causing injuries to others but 16 peaceful protesters were detained for merely protesting peacefully to protect the health of the people and the environment of Kuantan?" Thevarajan asked in a statement.

He was referring to the incident on Sunday where Himpunan Hijau protestors were forcefully arrested when demanding the shutdown of the controversial rare earth processing factory.

Sixteen, including Lowrey , were arrested and brought to Kuantan District Police Station (IPD Kuantan).

Two of those arrested were brought to Hospital Tengku Ampuan Afzan (HTAA) after sustaining injuries during the arrest.

Later, the protesters, who gathered at the IPD Kuantan in support of the 16, were allegedly verbally abused and physically attacked by some 15 unidentified individuals, right in front of police officers.

It is believed that the attackers were the same group who attacked the Kuantan DAP office last month.

While demanding a thorough probe over the insident, Thevarajan said the “thugs” should be arrested and brought to justice.

He added that Abdul Aziz and his officers should be held accountable and accorded disciplinary action for neglecting their duties.

"Any failure to conduct such investigation and arrest the thugs and discipline the police officers involved would only go to show that the police force are condoning violence and siding with Lynas Corporation," Thevarajan said.