Increasingly frequent terrorist attacks are becoming a growing threat to the global economy, finance chiefs from the world's leading economies said Sunday.

Earlier this month 84 people were killed in Nice when a Tunisian truck driver -- suspected to be inspired by the Islamic State jihadist group -- ploughed a 19-tonne vehicle through a holiday crowd. That followed Paris attacks last year which left 130 dead.

Kabul mourned Sunday after its deadliest attack for 15 years killed 80 people and left hundreds maimed the previous day, reigniting concern that Islamic State was seeking to expand its foothold in Afghanistan.

Last week a German-Iranian gunman -- believed not to be connected to the Islamic State group but "obsessed" with mass killers -- shot dead nine people in the German city of Munich before killing himself.

"We condemn, in the strongest possible terms, the recent terrorist attacks," G20 finance chiefs said in a communique after meeting in the Chinese city of Chengdu, adding that terrorism was one of the issues that "complicate" the economic environment.

France's finance minister Michel Sapin said the concept of terrorism as an economic risk itself was new, but its inclusion in economic analyses was now "normal".

"The world has already experienced terrorist attacks, the world experiences regional destabilisations," he told AFP. "But today the frequency of attacks creates a new situation of uncertainty, which is at least as damaging as regional destabilisations or a regional conflict.

"That can have economic consequences that are just as important," he said.

The G20 has long promoted efforts to combat financing of terrorist activities, particularly the work of the Financial Action Task Force. US Treasury Secretary Jacob Lew told reporters the meeting "reaffirmed our solidarity and resolve to fight terrorism in all its forms and wherever it occurs, and strengthening our efforts to prevent financing of terrorism".

Sapin pointed out that funding for what he called "low-cost terrorism", carried out domestically using methods that cost attackers relatively little, must also be addressed.

In a report ahead of the G20 meeting, IMF staff cited terrorism as an "ongoing concern", among others including geopolitical tensions, climate-related factors and diseases.