(Image Credit: Alexei Druzhinin/Presidential Press Service/AP)

MOSCOW - A spokesman for Vladimir Putin has confirmed that the Russian president suffered a "muscle strain" before attending a summit of world leaders in September, but denied that the injury has caused him to postpone a series of foreign trips and curtail his activities in Moscow.

"We have repeatedly said that such ideas do not have any foundation," Kremlin spokesman Dmitri Peskov said in a statement, according to the Interfax news agency.

"Every athlete has many injuries, especially those who play sport actively and on a daily basis, like Putin. He has trained for a long time, practically semi-professionally," he added.

The comments came after a string of news reports fueled speculation that the injury to Russia's longtime leader was affecting his travel and work plans. A Russian news report today said Putin sustained the injury during a stunt in which he flew with a flock of migrating cranes in a motorized hang glider just before the APEC summit in Vladivostok, in Russia's far east.

PHOTOS: Vladimir Putin Flies With Rare Siberian Cranes

"According to two people very close to the Kremlin, the president really is experiencing health problems, which are connected to an old injury that flared up after his flight with cranes," the newspaper Vedomosti reported.

"After the flight, it was very noticeable that he had a limp at the APEC summit in Vladivostok," the report said of the early September event.

The Kremlin spokesman did not address the bird reports, but issued the statement in response.

Reuters, citing unnamed government sources, reported last week that Putin had suffered a back injury that could require surgery.

The Kremlin also dismissed that report, saying "This does not correspond to reality."

Putin, who turned 60 last month, is known as an avid sportsman who is keen on being photographed participating in macho activities that he recently admitted were publicity stunts. In recent years, he has gone horseback riding bare-chested, dived for ancient treasure, bobsledded, skied, practiced judo and tagged polar bears and tigers, all in front of the cameras.

Recently, however, Putin has canceled or postponed foreign trips to Pakistan, Bulgaria, Turkey, India and Turkmenistan, fueling speculation that something is amiss.

He also announced that he would work more from home, claiming it is to decrease the impact of his motorcade on Moscow's already notorious traffic. The Kremlin also announced this week that Putin will postpone his annual call-in question session until the summer. But it brushed off any suggestion that the change resulted from his injury or the recent wave of opposition protests, saying it's best to hold the event when the weather is warmer.