(Adds analyst comment)

By Darya Korsunskaya

SOCHI, Russia, Sept 18 (Reuters) - Russian President Vladimir Putin issued a rare rebuke to Prime Minister Dmitry Medvedev's government on Tuesday, criticising its fiscal plans and accusing cabinet ministers of failing to act on orders he issued after returning to the Kremlin in May.

Putin's comments, in a meeting on budget strategy in the Black Sea resort of Sochi, suggested his patience was wearing thin with Medvedev just four months after the formation of his new government.

The 59-year-old Kremlin leader, who has dominated Russia since 2000, said that the three-year draft fiscal plan failed to take into account commitments in the decrees he issued after returning to Russia's highest office.

"If everything remains as laid out in the (budget) plan, then some or other of the points of these decrees cannot be implemented, I already see this. But they must be implemented," Putin said.

Putin's comments ran counter to his typical leadership style, which is based on strong loyalty to his political allies and continuity in government, and where disputes are rarely aired in public.

They were made in Medvedev's absence, as the prime minister was outside Moscow chairing a meeting of his 'open government' initiative, a forum widely criticised as a talking shop that has generated few worthwhile policy results.

Putin has been Russia's paramount leader since Boris Yeltsin resigned in a New Year's Eve speech in 1999 leaving him the presidency. Putin steered Medvedev into the presidency when he faced constitutional limits on serving a third consecutive term.

After the two switched jobs in May with Putin's return to the presidential office, speculation has grown that Medvedev could be ousted.

"If Putin really intends to change the prime minister and the government for a stronger team in the autumn - and I don't think there is any other choice - of course he needs citizens to understand why he is doing it," said Nikolai Petrov, analyst at the Moscow Carnegie Centre.

REPRIMAND

Putin called on Medvedev to reprimand two cabinet ministers for failing to implement measures contained in the batch of decrees setting out the policy priorities for his six-year term.

In addition to raising questions about Medvedev's authority, Putin's comments also raised doubts over Russia's commitment to balancing the budget over the medium term after heavy spending ahead of the presidential election in March.

Andrei Piontkovsky, a political analyst at the prestigious Russian Academy of Science, said that there are signals that show Medvedev may not have long as Putin's prime minister.

On the fourth anniversary of a five-day war with neighbouring Georgia, a group of Russian officers accused Medvedev, who was then acting as president of indecision at the time and having been "kicked" into action by Putin.

"This is a derisive slap at Medvedev's self-esteem in a series of humiliations," he said, adding that there was speculation that broad personnel changes could be expected in the government in the coming months.

"Medvedev is no good as Prime Minister And Putin has had enough of it."

Putin singled out for criticism Labour Minister Maxim Topilin and Regional Development Minister Oleg Govorun.

He said that, while it was not his personal responsibility to reprimand ministers, he was drawing Medvedev's attention to "the need to issue a reprimand to the Minister of Labour and the Minister of Regional Development."

"The work of a minister implies personal responsibility for the sector. And if something scheduled has not been implemented, then this responsibility should be borne," Putin said.

Putin said that despite his earlier order to the government to produce a plan for pension reform by the end of this month, no plan had yet been produced.

He also said that the government had failed to produce proposals for accelerating the development of Siberia and the Far East, also called for in his earlier presidential decrees.

The budget plan is due to be formally discussed by Russia's cabinet on Thursday. Putin's harsh criticisms mean that the plan is unlikely to be adopted in its present form. (Additional reporting by Nastassia Astrasheuskaya, Writing by Jason Bush and Thomas Grove; Editing by Douglas Busvine)