Putin, in what looked like a tacit acknowledgment that he is virtually certain of a second term after the 14 March poll, immediately signed a decree naming Deputy Prime Minister Viktor Khristenko as acting prime minister, a Kremlin spokeswoman said on Tuesday.
One Russian political analyst said Kasyanov's dismissal had been widely expected and that firing the entire government was a technical condition for that - however, he expected little overall change on the assumption that Putin will be re-elected.
"In accordance with article 117 of the Russian Constitution, I have decided today that the government is to resign," Putin said in a live television broadcast.
"This decision is not linked to any assessment of the activity of the former government, which I believe on the whole to be satisfactory," he said.
"It is dictated by a wish once again to set down a position on how policy will develop in the country after 14 March, 2004."
Putin has long expressed impatience with Kasyanov, who is associated with the former administration of Boris Yeltsin, for not proceeding quickly enough with reform and not producing
strong enough economic growth.
Sergei Markov, an analyst at Moscow's Institute of Political
Studies said: "It is not the firing of the government. It is the
firing of Mikhail Kasyanov. According to the constitution, Putin
can not do it without firing the whole cabinet.
"I think that the team of reformers headed by (Economy
Minister) German Gref will keep their positions...I do not expect any big change."