Police believe the explosion that occurred near the Nibong Tebal Barisan Nasional (BN) operations room was a planned work of mischief to create tension in the state.

Penang police chief Datuk Abdul Rahim Hanafi said it was planned by a group well-versed in using the improvised explosive device (IED), placed in a heap of garbage at the ceramah site.

"Police found two IEDs in the rubbish heap and from our investigation, we believe they were not meant to cause injuries, but to create fear and trouble.

"We are further investigating the incident to track down those involved," he said after visiting the scene of the explosion today.

Abdul Rahim said that after the first explosion, police including a forensic team who went to the scene at about 3am, found another IED which they immediately detonated.

He said the two IEDs had been timed by the culprits to explode at different times.

In the 10.15pm incident, a 35-year-old security worker was injured by flying debris from the explosion.

At that time too, Penang Gerakan chief Datuk Teng Hock Nan was giving a ceramah (talk) at the site which was attended by more than 3,000 people.

Abdul Rahim said the cigarette pack-sized explosive was not life threatening and the victim was only injured on his right calf.

He disclosed that Penang police had set up a special team headed by their CID chief, SAC Mazlan Kesah to investigate the incident and so far, they had recorded statements from seven witnesses.

Abdul Rahim said police viewed the incident seriously and warned that stern action would be taken against individuals out to create chaos in the state.

"There is a closed-circuit television camera (CCTV) near where the explosion occurred but it has been found to be not functioning and we are investigating the case under Section 6 of the Explosives Act 1957," he added.

Meanwhile, Abdul Rahim assured that security in the state was under control throughout the 13th general election (GE13) campaign period, so the public needed not worry about attending ceramah and other campaign activities.

Police had before this, arrested 11 men found to be carrying dangerous weapons including parang while putting up political party flags in George Town and Butterworth.

Abdul Rahim also advised political parties wanting to hold ceramah, to first apply for a police permit so that the police could check on the locations and beef up security at the ceramah sites.

Until last night, 159 ceramah had been held and 89 police reports related to the election campaign lodged, with the police opening seven investigation papers.

The Nibong Tebal parliamentary constituency which has 59,345 voters will see a three-cornered fight involving BN's Datuk Zainal Abidin Osman, PKR's Datuk Mansor Othman and independent candidate Teng Kok Pheng.

In the last general election, Tan Tee Beng who contested on a PKR ticket, defeated Zainal Abidin with a 3,087-vote majority.

On the IED explosion, Zainal Abidin, the state Umno liaison chief, said Penang Umno condemed the action by irresponsible quarters out to cause public fear so as to deter them from attending BN-organised ceramah.

"Previously, only hundreds would attend our ceramah but now thousands since the election campaign began, so certain quarters are worried about this.

"The incident will not dampen our spirit but will instead drive is to work even harder to win back Penang from the opposition pact."

He said Penang Umno sympathised with the injured victim, who was understood to be traumatised by the incident.

Several residents living near the BN operations room when met, said the second explosive detonated by the bomb disposal unit was louder than the first.

One of them who wished to be identified only as Siew, 47, said she rushed home from the ceramah to save herself after the first explosion and was later awakened from sleep by the second explosion.

Another witness, Rasyadah Rosli, 50, said she was saddened by such an incident as it could create chaos in this general election.

"The contesting parties should think about public safety and not try to sabotage their opponents as the outcome could be detrimental or even fatal. Who should be responsible for this?" she said.

Meanwhile, Parti Keadilan Rakyat (PKR) in a press release condemned the act of terror that happened in Nibong Tebal.

PKR de-facto chief, Datuk Seri Anwar Ibrahim said PKR and Pakatan Rakyat (PR), condemned the culprits who are responsible for these bombs, explosions and arson.

"We have nothing but contempt for those who would cynically endanger Malaysian lives. I appeal to all Malaysians, particularly those from Penang, to be vigilant, stay calm and not be swayed by rumours that may arise, " he said.

He added, he had commend the Penang Police Force for their quick response and actions and the State Police Chief Datuk Abdul Rahim Jaafar for his stern warning to anyone trying to create chaos and the setting up a task force to investigate these incidents.

PKR and PR have made it clear in no uncertain terms that we stand against political violence in any form. We also send our regrets and sympathy to the security guard who was injured in the Nibong Tebal incident.