Sonia Gandhi welcomed Prime Minister and his wife Gursharan Kaur who also accompanied him at the dinner with flower bouquets.
Earlier, several other leaders of the Congress like Shriprakash Jaiswal, Janardan Dwivedi and AK Antony were seen arriving at UPA chairperson's residence.
A momento signed by all the Congress Working Committee members was handed over by Sonia Gandhi to Singh to express their appreciation for his stewardship of the UPA government for a decade.
Dr. Manmohan Singh on Tuesday bid his staff farewell, just days before he is scheduled to demit the office that he occupied for a decade.
Thanking the staff in South Block, where the Prime Minister's office is located, Dr. Singh said they had all served the nation well, and wished them all success in their future endeavours.
"You have served the nation well. God bless you," he said.