Prime Minister Manmohan Singh with National Advisory Council (NAC) Chairperson Sonia Gandhi and other council members at a meeting in New Delhi

As he prepares to demit office, Prime Minister Manmohan Singh has written farewell letters to leaders of various countries, including US President Barack Obama, former Chinese Premier Wen Jiabao and Russian President Vladimir Putin.Dr Singh, who also wrote to German Chancellor Angela Merkel, has generally conveyed his thanks to them while recalling how they had worked together all these years, sources said.Mr Wen has sent his response to Dr Singh.In his hand-written letter, the former Chinese Premier has expressed his admiration for Dr Singh's leadership and helping in fostering better relations between the two countries, the sources said.Dr Singh and Mr Wen met over a dozen times as they enjoyed good rapport.Mr Wen, after demitting office, showed a special gesture of hosting a lunch for Dr Singh when he visited Beijing last year.Recalling their relationship, Mr Wen had remarked that the two leaders had been like "two drivers with steady hands on the wheels, driving in the right direction."Dr Singh and Mr Obama also had three Summit-level talks besides meeting several times on the side-lines of multilateral fora since the US President took over in 2009.

Similarly, Dr Singh has met Mr Putin a number of times, including having annual Summits.