MOSCOW, Oct 29 (Reuters) - Russia’s gross domestic product (GDP) rose 3.4% year on year in September, the economy ministry said on Friday, after a 3.7% increase in the previous month. The ministry also said GDP grew 4.6% in January-September compared with the first nine months of 2020 and was up 4.0% year on year in the third quarter alone. (Reporting by Darya Korsunskaya, writing by Maria Kiselyova)