Najib Abdul Razak said the spreading of false information through social media and by former leaders with the aim to topple the democratically elected government is a new threat to the country that needs to be countered.
The prime minister said attacking hearts and minds through the dissemination of false news and defamation was dangerous and it was being carried out by certain parties who had their own political agenda.
As such, Najib said the people should rise up together with the government to defend the country against these elements which could threaten its peace and prosperity.
"Defending our country does not only mean from attacks by troops from outside the country, but the more dangerous forms of attack are those against our minds and hearts.
"When our minds and hearts are attacked by news, propaganda as well as false information and defamation or 'fake news' coming out through social media or from certain leaders in order to topple a government, this is the greatest threat, and we will fight all out against it," he said.
Najib said this when officially opening the 'Negaraku: 1Malaysia Community' programme in Taman Tasik Sultan Abu Bakar in Pekan today.
The event was also attended by Communications and Multimedia Minister Salleh Said Keruak and his deputy Jailani Johari.
Also present were the state Women and Family Development, Communications and Multimedia Committee chairperson Shahaniza Shamsuddin and Bernama editor-in-chief Zakaria Abd Wahab.
According to Najib, following the spread of the false allegations, many measures and action taken by the government for the good of the people had been misinterpreted, giving rise to various controversies.
"As a government we've done many things (for the people)...however, when there are rumours which try to distort things, even good things can become bad and controversial, such as the handing out of the 1Malaysia People's Aid (BR1M)," he said.
Similarly, he said, when the government found a strategic partner for Proton Holdings Berhad, the action was misconstrued as selling the company to China, when in fact it was a move to strengthen the company's position and save the jobs of its employees.
Meanwhile, Najib said every citizen in the country, regardless of rank, race or religion, was obliged to defend its sovereignty and security.
"Our base is the same, that is Malaysia, no matter if we are ordinary citizens, leaders or kings...imagine if we don't have a country, like the Rohingyas living in Myanmar stateless.
"Just look at it on the television, day and night, their lives are in grave danger, when they do not have citizenship, they have to face whatever draconian measures thrown against them, being raped and burned alive.
"So when we are granted citizenship, it is most valuable to us, and as citizens, we must defend it because it is our country, this is the place of our birth, our land, and where we will one day be buried," he said.
At the event, Najib also presented prizes to winners of the national-level 1Malaysia Community Award 2016, with first place going to the 1Malaysia Community from Mukim Ayer Hitam, Johor.
Second place went to the 1Malaysia Community in Felda Keratong 3, Pahang, followed by the 1Malaysia Community from the Seri Perlis 2 Public Housing Project in Kuala Lumpur, with each team taking home grants of between RM4,000 to RM10,000, and a certificate.