Twitter has released a huge cache of pictures, videos and other information related to “potentially state-backed information operations” on the social network.

The data, comprising hundreds of gigabytes of tweets and media, are linked to thousands of accounts thought to originate from Iran and the Russian Internet Research Agency.

Twitter announced it had discovered activity related to the accounts early in the year but the micro-blogging site previously kept the full details private.

“We are making this data available with the goal of encouraging open research and investigation of these behaviours from researchers and academics around the world,” wrote Vijaya Gadde, Twitter’s legal, policy and trust and safety lead, and Yoel Roth, head of site integrity.

From more than 4,500 accounts identified as linked to potential information operations, 3,841 come from Russia and a further 770 are believed to be linked to Iran.

The data includes more than 10 million tweets and more than two million pictures, videos or other media dating back to 2009, made available on its Elections Integrity Hub.

Twitter has already shared the archive of information with a small number of specialist researchers to promote “shared understanding” and insisted “that this level of transparency can enhance the health of the public conversation on the internet”.

Vijaya and Roth wrote: “We will continue to proactively combat nefarious attempts to undermine the integrity of Twitter, while partnering with civil society, government, our industry peers, and researchers to improve our collective understanding of coordinated attempts to interfere in the public conversation.”

Since 2016, Twitter has been under pressure from politicians around the world to investigate underhand attempts by states and other actors to influence political events.

Damian Collins, chair of the parliamentary fake news inquiry, has repeatedly called on Twitter to release any information about state-backed campaigns which targeted UK politics or the Brexit vote after Russian-backed accounts were found to have interfered with the 2016 US Presidential election.

An investigation by the Press Association in March 2018 revealed at least 154 accounts from the Internet Research Agency had sent more than 2,400 tweets about Brexit, UK politics, immigration and the 2017 general election.