MOSCOW, October 15 (RIA Novosti) - Clinical trials of a new swine flu vaccine on children, scheduled to start in Russia on October 15, has been postponed for several days, a spokesman for the research center involved in producing the vaccine said on Thursday.

Timofei Peshkov said talks with research centers, which are to conduct the tests, had not finished on time.

Earlier Peshkov told RIA Novosti that testing of the vaccine on children was to start at Clinical Hospital No. 1 in Russia's western city of Smolensk and at the Influenza Research Institute of the Russian Academy of Medical Sciences in St. Petersburg.

A spokeswoman for the hospital in Smolensk confirmed the information, saying the talks are ongoing.

However, a spokeswoman for the Influenza Research Institute in St. Petersburg denied Peshkov's statement, saying no testing of a swine flu vaccine on children would be held at the institute.

"I can assure you that children will not be vaccinated at the Influenza Research Institute," she said.

Earlier this week, Russia's health watchdog Roszdravnadzor registered two Russian-produced vaccines against the A/H1N1 virus, also known as swine flu. After clinical tests proved the vaccines were safe and could be used for vaccination of adults, Roszdravnadzor permitted testing of the vaccines on children.

Russia's deputy health minister earlier said at least 35.5 million single doses of the new vaccine are to be produced by the end of the year.

Russia's top sanitary official said earlier this month that a total of 570 swine flu cases have been officially confirmed across Russia, with 491 cases among people who traveled abroad. No Russians have died of the virus.

According to the latest report from the World Health Organization, 340,000 cases of swine flu have been confirmed throughout the world and 4,100 people have died from the virus as of September 27.

Last week, a large-scale immunization campaign against swine flu started in the United States.