The discussion was organised as part of the centenary celebrations of the late diplomat.
Panelists including former Indian High Commissioner to Sri Lanka N N Jha and former Ambassador to US Meera Shankar spoke about his role in handling the Sri Lankan issue.
"GP ensured that the country (Sri Lanka) remained united. It is his greatest achievement. Tamils in Sri Lanka adored him while most of the Sinhalese had faith on him," said Jha.
Shankar said Parthasarathi had mentioned to Sri Lankan government that he could not see any role for Indian military in the country.
The panelists felt that India should invest more in Sri Lanka to counter China's growing influence there.