The chief minister was seated next to the Prime Minister and the two briefly chatted and smiled in between speeches at the Congress which was attended by a host of foreign delegates and Indian scientists.
This was their first meeting since September last year after the Trinamool Congress walked out of the UPA over FDI multi brand retail.
Also present on the dais was President Pranab Mukherjee who inaugurated the five-day meet.
It also apparently provided a good photo opportunity for television crew and photo journalists.
At one point, when there was a little commotion from the audience in the stadium balcony during Dr Singh's address, Ms Banerjee got up and sought to know the reason for it.
Later, she was seen instructing the organisers to set right the sound system as Dr Singh's speech was barely audible to those seated in the balcony.
People responded with applause as an SPG official adjusted the microphone after which the Prime Minister's speech was audible.
"Please look at Bengal. If Bengal is developed, then India is developed," Ms Banerjee urged the Manmohan Singh government in her speech.
Ms Banerjee has repeatedly alleged that the state was not receiving any support from the Centre to tide over its financial crisis and has demanded a three year moratorium on interest payment.