The managing editor of technology website Platformer, Zoe Schiffer, tweeted that employees were not given details about why the offices were temporarily closed until Monday, November 21. However, in a follow-up tweet, he said: “We’re hearing this is because Elon Musk and his team are afraid employees are going to sabotage the company. They’re also still trying to figure out which Twitter employees to cut off access for.” It comes as a new wave of Twitter workers are believed to be leaving the company following an ultimatum from new owner Elon Musk that staff sign up for “long, high-intensity hours” or quit. Mr. Musk has not publicly commented on these latest reports. The Tesla boss’ ultimatum marks another move to revamp Twitter, following its $44 billion acquisition of the social media platform last month. On Wednesday, Musk emailed Twitter employees that they had until Thursday to decide whether they wanted to stay at the company to work tough hours or take a three-month severance package. He said that to “build an innovative Twitter 2.0” the company had to be “extremely tough”. The world’s richest man warned that employees who did not click on a link confirming “you want to join the new Twitter” by 5pm New York time on Thursday would be deemed to have resigned. In a video posted online, a group of people claiming to be Twitter employees counted down the seconds, saying they were “going to get fired.” But in an email to staff on Thursday, he softened his earlier tone, writing that “all that is required for approval is that your manager takes responsibility for ensuring that you make an outstanding contribution.” Employees are also expected to have “face-to-face meetings with your colleagues at a reasonable rate, ideally weekly, but no less than once a month.” Mr Musk tweeted that he was not worried about resignations as “the best people stay”, adding: “And we just hit another all-time high in Twitter usage… Let that sink in…” He then posted some weird tweets, including a skull and crossbones emoji. This was followed by a post showing a photo of a freshly dug grave at a funeral, with a Twitter logo on the epitaph and the same covering the face of a person dressed in black kneeling next to the headstone, sticking two fingers up. Read more: Is this the end of ‘big tech’? “Twitter employee’s laptop wiped and accounts locked” Twitter employees have repeatedly posted the greeting emoji online, which has become a symbol of solidarity that someone has left the company. Musk’s takeover saw drastic changes at Twitter, including firing the company’s board and top executives, eliminating remote work and killing off half the workforce. He also announced that Twitter will charge users $8 a month for blue checkmarks to verify the authenticity of a user’s account.