By Deepa Babington ATHENS (Reuters) - Word of concessions by Greek Prime Minister Alexis Tsipras in Brussels had barely reached Athens on Monday when one of his own party's lawmakers, Yannis Michelogiannakis, had already decried them as a "tombstone" for Greece. "How can you cut a deal that will increase suicides and make people poorer?" he told Greek television late on Monday, hours after Tsipras presented new proposals to European creditors under the threat of a banking collapse and a default. Michelogiannakis, a former Socialist and doctor who made headlines by joining Syrian refugees on a hunger strike, is just one of several mavericks in Tsipras's ruling Syriza party who could buck the party line and vote in parliament against a painful deal to keep Greece afloat and in the euro zone.