Russian PM Vladimir Putin has joked that he and his Italian counterpart Silvio Berlusconi could stay in their jobs until the age of 120.
Mr Putin was responding to Mr Berlusconi's offer at an informal meeting in Russia to help fund research into extending the average lifespan.
Mr Berlusconi pointed out that it could be difficult to remain in a job with such a heavy workload for so long.
He said he had not managed to take a single day of holiday all year.
Mr Berlusconi was visiting Mr Putin after they attended a global policy forum in Yaroslavl, north of Moscow. The two have a history of cordial relations.
Mr Berlusconi said the institute he was planning to help finance would research ways of extending lives to 120, but with a smile added that he had "been told that leaders will live much longer lives".
Mr Putin replied: "So we will be prime ministers until at least the age of 120?"
Mr Berlusconi said that would be unlikely, because prime ministers have a lot of work and "often get tired".
"You won't believe it, I haven't had a single day of holiday this year," he said, and suggested Mr Putin had also had "no time for leisure" in recent weeks.
Mr Putin said he would speak to Mr Berlusconi at a later date about "a couple of days of joint holiday".