KUALA LUMPUR, May 9 ― Barisan Nasional (BN) chairman Datuk Seri Najib Razak has ordered immediate action to be taken to prevent further "cyberattacks” on Malaysian citizens and organisations following a massive spam on polling day today.

"I condemn the ‘Spam Calls’ received by many BN leaders from overseas numbers. Phones that have been ‘spammed’ cannot function as usual.

"Apart from that, many BN websites cannot be accessed. I have ordered immediate action to be taken,” he posted on his Twitter account.

Najib had retweeted an earlier post from his cousin and Umno vice-president Datuk Seri Hishammuddin Hussein who was among the party’s senior members that had been deluged with phone calls from unknown numbers.

"Just finished voting and realized all these missed calls from unknown numbers. Strange,” tweeted the incumbent Sembrong MP who is defending his parliamentary seat this election.

Other BN leaders who were spammed with the mystery calls were Sabah BN leaders Datuk Seri Abdul Rahman Dahlan, Datuk Seri Salleh Said Keruak, and Datuk Seri Azalina Othman Said.

Leaders from the Opposition Pakatan Harapan (PH) pact have also complained of having their phones jammed with these anonymous calls. Among them were DAP secretary-general Lim Guan Eng who claimed it was an attempt to sabotage the elections.

PKR deputy president Datuk Seri Azmin Ali was reportedly victimised too. According to a report in news portal Malaysiakini, the incumbent Gombak MP claimed his handphone, emails and Facebook account were hacked before 6am today.

The politicians were not the only ones affected. Chief Secretary to the Government Tan Sri Ali Hamsa said he had been spammed 488 since 7am and branded it  a "cyberattack by irresponsible parties to disrupt #PRU14”.

Malaysian organisations including human rights group Suaram, electoral reforms group Bersih 2.0, DAP mouthpiece Roketkini and PKR-linked research outfit Invoke Malaysia are said to be down.

The Malaysian Communications and Multimedia Commission (MCMC) has acknowledged receiving "numerous complaints today of phones ringing and then the call drops” and advised people against answering them.

It said its initial investigation points to a BOTS attack which is initiated anonymously from various sources with differing targets.

The MCMC said it is still investigating the matter with local telecommunications service providers and promised stern action against the culprits.