Investing.com -- Elon Musk's tunneling startup, the Boring Company, recently closed an investment round that values the company at around $20 billion, according to reporting from The Wall Street Journal, citing people familiar with the matter. The company made an unusual demand of some investors in the latest funding round, requiring them to help build the business if they wanted to participate.

The Boring Company told some investors that participated in the round that they would have to help recruit employees or assist with business development, such as making introductions to government officials in places where the company might build tunnels, according to the WSJ report. The company described to prospective investors some of the roles it is seeking to fill, the people said.

If investors fail to provide viable candidates for such jobs, the Boring Company has the right to buy back some of their shares, the people said. Musk wrote "True" on X Thursday in response to the article.

The Boring Company, which builds machines that it claims can dig underground more cheaply than traditional construction firms, was spun off from SpaceX in 2018. The company owns a transportation network under the Las Vegas Strip and has pitched projects in cities including Baltimore, Chicago and Los Angeles.

The company has a new loop under development in Nashville, which it is privately funding. Musk's rocket company SpaceX went public in June in a record-setting IPO that raised $86 billion from Wall Street and delivered a windfall to investors.