Thousands of Twitter accounts, including high-profile ones belonging to Forbes, Amnesty International and the BBCs North American service, were compromised on Wednesday, resulting in them tweeting propaganda related to Turkeys escalating diplomatic conflict with Germany and the Netherlands.
The hijacked accounts have all posted the same Turkish-language tweets with a Nazi swastika followed by the hashtags #Nazialmanya and #Nazihollanda (#NaziGermany and #NaziHolland).
The text after the hashtags reads: "This gives you a little #OttomanSlap," and makes reference to April 16th -- the day Turkey will hold a referendum on constitutional changes that would consolidate President Recep Tayyip Erdogan's power and potentially allow him to remain in office through 2029.
The tweets also include a link to a pro-Erdogan video on YouTube.
The attackers also changed profile pictures and header images for some targets, changing the main image to a Turkish flag and the profile picture to a Turkish-style coat of arms, reported the Guardian.
Several users noted that all hijacked tweets appear to have been linked to Twitter Counter, a Netherlands-based analytics application.
Twitter Counter was previously targeted in a November 2016 attack that caused some high-profile accounts to spread spam. At the time, the company said it has over 2 million users.
The attack comes amid heightened tensions between Turkey and the Netherlands, after the Dutch government barred two Turkish ministers from speaking to expatriates in the Netherlands ahead of the referendum.
In response, Erdogan accused the Dutch government of acting like "Nazi remnants", and Turkey suspended high-level diplomatic relations with the Netherlands on Tuesday. Erdogan also accused Germany of behaving "like Nazis" after the government banned Turkish rallies ahead of the referendum.
Forbes, Sprint CEO Marcelo Claure, the UK Department of Health, Reuters Japan, BBC North America, Duke University and Amnesty International were all affected among several other charities and universities.
BBC North America confirmed that it had been caught up on the hack, tweeting: "Hi everyone - we temporarily lost control of this account, but normal service has resumed. Thanks."
In a statement, Twitter said that it was "aware of an issue affecting a number of account holders this morning. Our teams are working at pace and taking direct action on this issue. We quickly located the source which was limited to a third party app. We removed its permissions immediately. No additional accounts are impacted."