San Francisco,  Elon Musk has brought an immediate end to remote work at Twitter for the remaining 50 per cent of the employees, warning them that "the road ahead is arduous and will require intense work to succeed".

In his first email sent to the employees, the new Twitter CEO said that "over the next few days, the absolute top priority is finding and suspending any verified bots/trolls/spam". Bloomberg first reported the news.

Musk warned that a weaker economic environment in the US would mean difficulties for Twitter and there was "no way to sugarcoat the message" about these challenges.

He also reportedly told employees that they should be in the office for a minimum of 40 hours a week.

Musk, however, said that he would only approve remote work on a case-by-case basis.

In March this year, then Twitter CEO Parag Agrawal had told employees that wherever you feel most productive and creative is "where you will work and that includes WFH full-time forever".

"Decisions about where you work, whether you feel safe traveling for business, and what events you attend, should be yours," he had told the staff.

Meanwhile, several top companies, including insurer Allianz and automaker Audi, have paused ad spend on Twitter in response to the Musk takeover.

Musk told advertisers on Wednesday that he had heard their concerns.

In his online meeting with advertisers, Musk told them how paid verification via Blue subscription service and support for a creator ecosystem could herald growth for Twitter.