Russian officials traced dead domestic poultry in several suburban Moscow districts to a single market Sunday as experts reported new outbreaks and tightened quarantines following confirmation of the presence of the H5N1 bird flu strain. The presence of H5N1, confirmed by tests late Saturday, was the first such outbreak to be recorded so close to the Russian capital. Four separate incidences of domestic poultry dying involved birds that were purchased at a market located just outside the Moscow city limits, federal agricultural oversight agency Rosselkhoznadzor spokesman Alexei Alexeyenko said. The market was closed Saturday and experts were trying to determine the original source for the birds on sale there, he said. On Saturday, Alexeyenko said tests had confirmed the H5N1 strain in poultry found dead in two districts where roughly two dozen birds had died - Odintsovo and Domodedovo. Results of tests taken in a third district where nearly four dozen birds died - Podolsk - were still pending, he said.