The Kremlin has played down a decision by Japan's prime minister to put off a visit to Russia amid speculation about President Vladimir Putin's health.
Yoshihiko Noda was quoted by Japanese media as saying he had postponed a planned visit because "President Putin's health condition is bad".
But Mr Putin's spokesman said no definite date had been agreed and he denied his work was being affected.
Reports suggest the keen sportsman, 60, is suffering from a bad back.
President Alexander Lukashenko of Belarus, which has close relations with Russia, told Reuters news agency this week that Mr Putin had recently "twisted his spine" playing judo.
Russian government sources told Reuters just over a month ago that the president was suffering from back trouble.
Mr Putin, who has not travelled abroad since a visit to Tajikistan on 5 October, is due in Turkey on Monday for a one-day visit.
'Working as before'
His spokesman, Dmitry Peskov, sought to play down the speculation, telling Itar-Tass news agency no hard date for Mr Noda's visit had been agreed, and he might now come to Russia in January.
In a separate interview for Russian tabloid Komsomolskaya Pravda, he said rumours about the president's health had been "blown out of proportion".
"He is working as before, and plans to continue working at the same pace," he said.
"He is also not planning to stop his sports activities, and, as any athlete, he may sometimes have pain in the back, an arm or a leg. This has never affected his work efficiency."
A Japanese government source told AFP news agency that Russian officials had informed their Japanese counterparts that Mr Noda's visit would have to be cancelled due to Mr Putin having an unspecified health problem.
Mr Lukashenko told Reuters in an interview in Minsk that he had been hoping to play ice hockey with Mr Putin but the Kremlin leader, who is famously a judo black belt, had postponed the match.
"He tells me: 'We are not prepared yet to take on your team'," he said.
"He has damaged his spine somewhere. In a judo match. He was on the mat and hurt his spine."
Previously there was media speculation that Mr Putin had hurt himself during a stunt on 6 September, when he flew a hang-glider alongside some rare Siberian cranes.
Shortly afterwards, he was seen limping, and grimacing, at a summit in Vladivostok.
However, the Russian leader's reported ill health has not stopped him receiving German Chancellor Angela Merkel and other international figures in Moscow in recent weeks.