Musk told Twitter employees that anyone who had not clicked on a link confirming “you want to be part of the new Twitter” by Thursday evening New York time would be considered to have quit.

“Whatever decision you make, thank you for your efforts to make Twitter successful,” the message said.

A copy of the message, which was reported by The Washington Post, was reviewed by Reuters. A person who had received the message at Twitter confirmed its content.

Twitter did not immediately respond to a request for comment from Reuters.

“Going forward, to build a breakthrough Twitter 2.0 and succeed in an increasingly competitive world, we will need to be extremely hardcore,” the message from Musk said. “This will mean long hours at high intensity. Only exceptional performance will constitute a passing grade.”

Read in Daily Maverick: “Musk publicly punishes Twitter engineers who call him out online”

Musk said Twitter would be “much more engineering-driven” under his leadership, adding that “those writing great code will constitute the majority of our team and have the greatest sway.”

Twitter laid off half of its workforce earlier this month shortly after Musk took control of the social media company. Musk has criticised Twitter’s spending and work culture and said the company needs steep cost cuts and a reboot of its services.

Some Twitter employees who had criticised Musk publicly tweeted earlier that they had been let go.

By Hyunjoo Jin and Fanny Potkin

(Reporting Hyunjoo Jin and Fanny Potkin, writing by Kevin Krolicki, editing by Louise Heavens)