Twitter users worldwide were unable to access the social-networking site for about an hour, with an outage that affected both mobile and web platforms.

Twitter said “an internal configuration change” was responsible for the outage.

On the web, users saw an error message that said, “Something is technically wrong. Thanks for noticing – we’re going to fix it up and have things back to normal soon.”

An error message in the Twitter app said, “Tweets aren’t loading right now.”

According to website DownDetector.com, Twitter began experiencing issues around 2.46pm New York time on Thursday (4.46am AEST Friday).

The highest concentration of user-reported technical problems were from Western Europe and the US. Australia was also affected.

Twitter service appeared to be restored about an hour late, about 3.45pm local time (5.45am AEST Friday).

Twitter’s support account said in a tweet at 4.15pm New York time, “Twitter is back up for some people, and we’re working to make sure our service is available to everyone as quickly as possible.”

The company said the outage was “due to an internal system change, which we’re now fixing. We’re sorry for the inconvenience and should be at 100% soon.”

Once Twitter service was restored, the downtime was an immediate subject of tweets.

“miss us?” Twitter posted on its main account.

The Twitter outage comes on the heels of a string of technical problems at Instagram recently.

On July 3, a technical glitch prevented Instagram users worldwide – as well as Facebook and WhatsApp users – from sharing or accessing photos and videos for much of the day.

That was less than a month after Instagram had an outage that lasted more than two hours, following two other major outages in June.

Twitter was out of commission just as Donald Trump – a frequent and aggressive tweeter – was hosting a so-called social media summit at the White House on Thursday afternoon local time.

The White House did not release a list of attendees, but those expected at the event included reps from conservative think tanks and “far-right internet personalities and trolls, some of whom have pushed conspiracy theories, lies and misinformation”, according to a CNN report.

Twitter and Facebook executives were not invited.

“A big subject today at the White House Social Media Summit will be the tremendous dishonesty, bias, discrimination and suppression practiced by certain companies,” Mr Trump tweeted earlier in the day, evidently referring to tech companies like Google, Facebook and Twitter.

-AAP