The function at 10, Janpath, Sonia's residence, was held as a mark of gratitude by the party whose coalition government 81-year-old Singh led for 10 long years.
A memento was presented to Singh with signatures of top Congress leaders and Union ministers and Pallam Raju read out the dedication inscribed on it in praise and honour of the prime minister.
Both Singh and his wife Gursharan Kaur were presented with bouquets and party leaders were seen scrambling for a photograph with the couple and Sonia Gandhi.
