The OECD has joined the Christchurch Call - which seeks to eliminate terrorist and violent extremist content on the internet.
Fifty five countries and 10 tech companies are part of the call, which was formed in the wake of the 15 March mosque attacks.
OECD Secretary-General Angel Gurría said since hosting the 2019 meeting that resulted in the Christchurch Call, the OECD has been driving a process to standardise how online platforms publish information about the terrorist and violent extremist content (TVEC) that appears on their services and the policies and procedures they have in place to address it.
Gurría said both countries and companies are struggling to combat the harm caused by terrorist or extremist online content while protecting fundamental freedoms and human rights.
"We have seen all too often the real-world harm that terrorist and violent extremist content online causes," he said in a statement.
"Joining the Christchurch Call and continuing to advance our work in this area is what the OECD is all about: like-minded governments, in consultation with experts from business, civil society and academia, collaborating to improve the evidence base and help to build better policies for better lives."
By formally joining the Christchurch Call, the OECD will "underscore the imperative of collective action," he said.
A 2020 OECD report on the approaches to terrorist and violent extremist content (TVEC) online highlighted the need for more reporting and more consistent reporting.
The report showed that only five of the Global Top 50 Online Content-Sharing Services were issuing transparency reports on TVEC and that, even among those five, the platforms differed substantially in how and what was reported.
The dearth of reports, and the lack of comparability among them, are critical barriers to assessing the industry's efforts to counter terrorist and violent extremist content online and their impact on fundamental freedoms, Gurría said.
The OECD is looking to develop a standardised reporting template to aggregate and compare reported information on terrorist and violent extremist content across platforms.
He said this work would directly advance the Christchurch Call's objective of improving transparency while remaining true to the principles of a free, open and secure Internet.