Shareholders of US Steel have approved the company's proposed takeover by Japan's Nippon Steel. The deal won overwhelming support at a special meeting on Friday.

Nippon Steel announced in December that it plans to buy the US firm for 55 dollars per share, offering a 40 percent premium on the trading price at that time.

The Japanese firm plans to complete the 14-billion-dollar buyout by September.

US Steel President and CEO David Burritt said the two companies are one step closer to "moving forward together as the 'Best Steelmaker with World-Leading Capabilities'."

Nippon Steel Vice Chairman Mori Takahiro described the shareholders' approval as "extremely gratifying."

He added: "From the outset, our goal has been clear -- to protect and grow US Steel in the US market for the benefit of all of its stakeholders through increased financial investment and the contribution of our advanced technologies."

The United Steelworkers Union is against the deal, and in March, US President Joe Biden also voiced his opposition.

The plan faces scrutiny from the Committee on Foreign Investment, a US panel that looks into national security issues.