Speaking as he and Chinese President Hu Jintao wrapped up joint military exercises at a training ground in the Ural Mountains, Putin said: "We have decided to renew flights of Russian strategic aviation on a permanent basis."

"In 1992 Russia unilaterally stopped flights by its strategic aviation in distant military patrol regions. Unfortunately not everyone followed our example and strategic flights by other states continue," he said, an apparent reference to the United States.

"This creates certain problems for ensuring Russia's security," he said.

The United States played down the Russian announcement.

"We have very good working relations with the Russians, with the Russian military," US national security spokesman Gordon Johndroe said in Texas, where President George W. Bush was on vacation, adding that the move was "an internal decision" by Putin.

Asked whether the patrols posed a security threat to the United States, Johndroe replied: "I don't think our military has those concerns about it."

Earlier in Washington, a State Department spokesman was more dismissive of Putin's announcement.

"If Russia feels as though they want to take some of these old aircraft out of mothballs and get them flying again that's their decision," spokesman Sean McCormack said.

Putin said the flights would resume from Saturday from seven aerodromes across Russia and would normally be in the air for up to 20 hours with the help of refuelling aircraft.

Primarily they would concentrate on major shipping routes and areas of Russian economic activity, he said, without specifying further.

He added that he hoped Russia's "partners" would "view the renewal of Russian strategic aviation with understanding."

The return of strategic flights is consistent with Putin's efforts to boost Moscow's status, which crumbled when the Soviet Union collapsed in 1991 and bitter Cold War rivalry with Washington came to an end.

The announcement came days after Moscow said its strategic bombers had begun exercises over the North Pole and just a week after Russian planes flew within a few hundred kilometres (miles) of a US military base on the island of Guam.

On Wednesday a top US commander said that Russian bombers had been making increasingly frequent flights approaching US territory for several months.

Both Britain and Norway's air forces have taken to the skies in recent months to monitor the renewed Russian air force activity, at a time when relations with Britain are in crisis over the poisoning in London of a former Russian agent, Alexander Litvinenko.

Shortly before Putin's announcement, a Russian air force official said long-range bombers were carrying out patrol flights on Friday in various parts of the world, including the Arctic, Atlantic and Pacific Oceans and the Black Sea.

"At present, there are several pairs of Tu-160 and Tu-95MC plans over the waters of the Atlantic and Pacific oceans, being escorted by NATO aircraft," ITAR-TASS quoted Russian Air Force spokesman Colonel Alexander Drobyshevski as saying.

"During the course of the day around 50 flights will be carried out" by the bombers and other aircraft, he said.

Putin has hit out at US global domination, saying earlier this year in a speech in Munich that Washington had "overstepped its boundaries in all spheres."

He has particularly attacked US plans to install parts of a missile shield in the new NATO states of the Czech Republic and Poland, describing such moves as a threat to Russia's security.

"Now there is money, and for Russia what is important is a balance of forces and to again equal the others, especially the United States," commented defence analyst Ivan Safranchuk of the Centre for Defence Information in Moscow.

Friday's exercise at the Chebarkul training ground were another demonstration of Russia's new found assertiveness, particularly in partnership with China.

Putin said that 7,500 personnel had participated in the exercises, from the six countries of the Shanghai Cooperation Organisation: China, Kazakhstan, Kyrgyzstan, Russia, Tajikistan and Uzbekistan.

While analysts have portrayed the group as an attempt to counter the Western-led NATO alliance, Putin denied this, insisting it was more a counter-terrorism organisation than a military one and was also aimed at economic cooperation.

earlier related report
Russia's strategic bombers: facts
Russia, which on Friday announced the resumption of strategic bomber flights, has a fleet of 80 long-range aircraft, most of them from the Soviet era and capable of carrying nuclear weapons.

The 37th Strategic Air Army consists of 64 Tupolev-95 "Bear" aircraft and 16 Tupolev-160 "Blackjack" planes, according to the London-based International Institute of Strategic Studies' publication "The Military Balance 2007."

Military publications group Jane's said Russia's strategic aerial capacity is inherited from the Soviet Union and has "declined significantly" since the mid-1990s.

In recent years, the emphasis has shifted towards conventional bombing missions in low-intensity conflicts and appears better prepared to provide support for combat troops in asymmetrical warfare, it added.

"Blackjacks" and "Bears" each carry eight 200 kilotonne Kh-55 nuclear missiles, which have a range of 3,000 kilometres (1,864 miles).

The "Bear", the first models of which entered service in 1955, is a four-engined turbo-prop with a range of more than 10,000 kilometres.

The "Bear H", which carries nuclear weapons, made its first flight in September 1979. It is expected to remain operational until 2010 to 2015.

The Tupolev 160 "Blackjack" is the counterpart to the US strategic bomber the B-1B. It can travel up to 14,000 kilometres depending on what weapons it is carrying. Its first flight was in 1981.

Russian strategic bombers are based in Engels, near Saratov, south of Moscow, and Ukrainka, near Svobodny, in Siberia.

The country's strategic air force also consists of about 60 Tu-22 "Backfire" bombers, which have a nuclear capacity but are used on conventional missions.