Social media giant Twitter appeared to apply a five-second delay that would slow access to sites – a process known as throttling – including to the New York Times, Reuters, Instagram and Blue Sky, another social network, the Washington Post reported on Tuesday.

The sites with slowed links included competitors to Twitter and news publications that have been on Twitter owner Elon Musk’s bad side due to critical reporting. The Washington Post tested the delays and found that if someone clicked a link on Twitter that would send them to another site, the link would open to a blank screen that lasted for a few seconds.

The delay seemed to involve only t.co links, a service that processes and abbreviates links posted to Twitter. By Tuesday afternoon, the issue appeared to be fixed with links opening within a second of clicking.

Musk has waged an ongoing battle on his detractors in the press. In April, Twitter labeled the BBC and NPR as “state-affiliated media”, a move that drew outcry from the outlets and their staff. On 12 April, NPR announced that they were quitting Twitter and their flagship page has not seen a new post since then.

That same month Twitter began marking links to Substack, an independent content publishing platform, as unsafe. This move came after Substack ​​announced a new feature, “Substack Notes” which offered a Twitter-like experience for the company’s user base of newsletter authors and their readers, some of whom are paying subscribers. Substack argued that Notes and Twitter don’t have to be competitors but should instead complement each other.

Twitter, now known as X, did not immediately respond to a request for comment from the Guardian.