Here are the latest developments:
PM Modi said from conflict zones to distant cities, terrorism "extracts a deadly price" and called for a long-term approach and a stronger role for the UN, adding that, global links of terrorists "offered a new threat to pluralist and open societies".
In a 10-point proposal on tackling global terrorism, PM Modi stressed on delinking terror and religion while isolating sponsors and supporters of terrorism. He said the world must act in unison and have one voice against terrorism without any political considerations.
World leaders in a joint statement raised the alarm over an escalating international movement of "foreign terrorist fighters". The leaders said they were determined to counter violent extremism, recruitment and to prevent terrorists from exploiting technology, including the Internet.
In an earlier statement at G20 and the BRICS meet held in its sidelines, PM Modi condemned the Paris attack in strong words. "Today, we meet in the tragic shadow of dreadful acts of terrorism. Combating it must be major priority for G20," he said.
The working sessions at the summit began with observing a minute of silence. "Standing in solidarity. The G20 working session begins with a moment's silence for victims of Paris Attacks," External Affairs Ministry spokesperson Vikas Swarup tweeted while posting pictures of the participating world leaders.
US President Barack Obama and Russian President Vladimir Putin have agreed on the need of UN-negotiated peace talks and a ceasefire in Syria, reported Agence France-Presse, quoting an US official.
The migrant issue and the war in Syria are also looming large on the summit in view of the Paris attacks. Many countries favour controlling the inflow of migrants -- a stand that has gained force after it was known that one of the terrorists used a fake passport to enter the European Union. US said it backs Turkey's stand and hopes to reduce the flow of migrants.
This morning, hours before the meet started under a heavy security blanket, a jihadist suspected to belong to the Islamic State blew himself up in southern Turkey, 800 km from Antalaya, injuring four policemen. Yesterday, Turkish soldiers kill four suspected IS militants near G20 summit site.
French President Francois Hollande cancelled his visit to the meeting in the wake of the Paris attack, in which 129 people died on Friday. "The Paris attack is an attack on the civilised world. We stand in solidarity with France," Mr Obama said a joint news conference with Turkish President Tayyip Erdogan.
PM Modi has repeatedly underscored the importance of having the United Nations arrive at a common definition of terror at the UN General Assembly, in public addresses while in the US and most recently, at the British Parliament last week.