Russian President Vladimir Putin on Thursday ordered surprise military exercises in the Black Sea region involving 7,000 troops and dozens of ships to test the army's battle readiness, the Kremlin said.

In typical Putin style, the order was presented to the Defence Minister Sergei Shoigu in a sealed envelope in the middle of the night at 4:00 am (2400 GMT), with the drills to start immediately.

Putin's spokesman Dmitry Peskov indicated the order was aimed at testing out the battle readiness of the Russian armed forces and said Moscow was not obliged to warn its partners of the plan.

"Today at 4:00 am the president of the Russian Federation and supreme military commander (Putin) gave the order to the defence minister to begin major military exercises in the Black Sea region," Peskov said.

"We are talking about major exercises, intended as a check," he added in a statement carried by Russian news agencies. He said the exercises would involve 36 ships and up to 7,000 troops.

A defence ministry source told the state RIA Novosti news agency that the military drills, which would involve live firing, were already under way and would be wrapped up by the end of the week.

Peskov said Putin had already warned the armed forces that they would be subject to sudden checks of their battle preparedness.

"If we remember what the president said at the council of the defence ministry a little time ago, then we will remember his words that the practice of sudden checks will continue," Peskov added.

Putin drew up the sudden order overnight while flying home from South Africa where he attended the summit of BRICS emerging economies in Durban.

Peskov said 36 ships from the Russian Black Sea Fleet's base in the Ukrainian Crimean city of Sevastopol and the Russian port of Novorossiisk would be involved in the exercises.

Aviation, paratroopers and special forces would also take part, Peskov said.

"According to international practice, exercises involving up to 7,000 people do not require us to inform our partners in advance," he said.

The defence ministry's chief spokesman Igor Konashenkov told RIA Novosti that the drills would involve 7,000 troops, up to 20 military jets and helicopters and 50 pieces of artillery.

Key littoral states on the Black Sea include Turkey, Ukraine and Russia's foe Georgia with whom Moscow fought a brief war in 2008. EU members Bulgaria and Romania also have a Black Sea coastline.

Peskov said the exercises would take place on three military test ranges on Russian territory.

Russia embarked on a major campaign of military reform after its war with Georgia showed up weaknesses in the reactivity of the armed forces despite the military victory over Tbilisi.

The government is seeking to make the army more responsive to the demands of modern warfare by modernising technology and shaking up command structures.

Independent military analyst Alexander Golts said that as long as the element of surprise was genuine, the exercises were a good idea "to test the battle readiness of the army".

Analyst Pavel Felgenhauer, a military commentator for the opposition Novaya Gazeta newspaper, said Putin was keen to make another display of Russian military might to the West.

"This is sabre rattling in the place nearest (to Europe) to make a demonstration of our intentions," he said.

The exercises represent a major test for Shoigu, one of Putin's closest allies who became defence minister late last year after previous incumbent Anatoly Serdyukov, the architect of the military reform, was implicated in a graft scandal.

RIA Novosti said that the manoeuvres come after a similar sudden exercise was ordered in February in Russia's central and southern regions that was the first unscheduled check of the armed forces in 20 years.

After those exercises, Russia's top general Valery Gerasimov said a number of systemic problems and shortcomings of military hardware had been uncovered.