[Russian President Putin takes part in a video link, dedicated to the start of natural gas supplying from mainland Russia to Crimea, in Moscow]MOSCOW (Reuters) - Russian President Vladimir Putin discussed topics including the situation in Syria during phone calls with Greek Prime Minister Alexis Tsipras and Egyptian President Abdel Fattah al-Sisi, the Kremlin said on Thursday. (Reporting by Peter Hobson; editing by Katya Golubkova)