Police arrested 18 Penang PKR Youth members and activists over a flash mob in conjunction with Prime Minister Najib Abdul Razak's visit to Permatang Pauh in Penang this morning.

The first group of 12 was rounded up after gathering in front of the Seberang Perai Polytechnic in Bukit Mertajam, where the prime minister is expected to join tens of thousands of people for a record breaking feast at 11am.

The second round of arrests started at 10.40am with three women, including PKR activist Siti Sharifah Ismail, hauled up. 

Siti Sharifah put up a brief struggle when she was taken away. About 11.45am, Bukit Mertajam PKR youth chief Ikwan Nasser was arrested. 

The 16, including state PKR Youth Chief Asrol Sani Abdul Razak and Seberang Perai Municipal Council member Ong Jing Cheng, were then taken to the Seberang Perai Tengah district police headquarters.

PKR banners were put up at the polytechnic gates and surrounding areas last night, with rallying calls to "Free Anwar Ibrahim" - the PKR de facto leader who is currently serving a five-year sentence a sodomy conviction.

The group aimed to highlight Anwar's incarceration, which the opposition claims was based on a fabricated charge.

PKR information chief Fahmi Fadzil in a statement later, said the arrests were a "big slap" to democracy in Malaysia.

"It shows that Najib does not respect democracy and freedom of speech as guaranteed in the Federal Constitution, especially for the youths.

"The youths who gathered today did not throw chairs or slippers at anyone but only carry placards peacefully to express their political stand.

"Are they a threat that they had to be nabbed by the police this morning?" he asked. 

State Pakatan Harapan youth chief Arif Bahardin confirmed later in the afternoon that the number of arrests had gone up to 18. 

He questioned the need to arrest the group as they were just attending the event, which was open to the public. 

He further queried the section of the Penal Code used to arrest the 18, and urged all of them to be released immediately. 

It is learned that the group were nabbed under section 105 of the Criminal Procedure Code pertaining to the arrest to prevent seizable offences.

All the 18 people, were, however, released later in the afternoon, after having their statements taken at the Seberang Perai Tengah police headquarters.