"The PM sounded desperate," Kadir wrote in his blog today.
"If things are as rosy as he and his propaganda machinery make it out to be in the mainstream media, he should not sound desperate."
Yesterday, Najib said that paying taxes is one of the pillars of patriotism.
The Umno-controlled New Straits Times reported Najib as saying that those who evade taxes are committing treason.
In his rebuff, Kadir said that Najib's words "are a very serious insinuation".
"Not everybody who does not pay tax is a tax evader. Many have mitigating reasons," he wrote.
"He is the PM and the Finance Minister, and he has at his disposal those billion-ringgit consultants and a spouse that goes around the world bringing in investments!
Kadir emphasised that Putrajaya has lost its trust among the public in the way they spend taxpayers' money.
"More and more people, I believe, are reluctant and unhappy to pay taxes because they hold the view that the government is lavish and corrupt."
The former journalist also went on to imply that all is not well with Putrajaya's coffers despite the government's assurances.
"All this while we have been told and assured repeatedly that everything is okay - the government has money, the Treasury is filled, revenue collection is good and billions of ringgit of foreign investments are flowing in," he said.
"So why should the PM, who is also the Finance Minister, sound so desperate?"
If Putrajaya is indeed facing financial troubles, then Najib must be held accountable, said Kadir.
"If there is something amiss about government finances, Najib only has himself to blame.
"He is the PM and the Finance Minister, and he has at his disposal those billion-ringgit consultants and a spouse that goes around the world bringing in investments!" - November 25, 2013.
~ The Malaysian Insider