NFL preseason games in 2020 have been cancelled, commissioner Roger Goodell announced in a letter to fans.

The preseason was called off amid the coronavirus pandemic, with the regular season due to begin on September 10.

In the letter, Goodell said this season would be unlike any other due to coronavirus.

"COVID-19 will continue to present a major challenge to nearly every area of American life. Football is no exception," he wrote.

"Every step of the way, our focus has been on the safety of players, coaches, personnel, fans and our communities. Our planning has followed the lead of medical experts and public health officials, including the CDC, the White House Task Force, governors and state health officials.

"As we have developed our 2020 playbook for the return of football, safety continues to be our first priority; that commitment will remain paramount as players return to the field.

"The NFL in 2020 will not look like other years. Players and coaches will be tested for the virus regularly, including every day for a while. Preseason games have been cancelled. Everyone in the team environment must follow rigorous health and safety protocols to keep themselves and each other safe.

"When there is a positive test, strict regulations will be enforced to isolate and care for that individual and to contain the virus before it spreads. Even the sideline will look different.

"And, state and local health guidelines will help determine whether fans will attend the games. These adjustments are necessary to reduce the risk for everyone involved.

"Thanks to the collaboration of the players and a lot of hard work from our clubs, especially their medical and training staffs, our plans are in place for the 2020 season."

There have been more than 16 million confirmed cases of coronavirus around the world, with the death toll exceeding 655,000.

The United States has seen more than 150,000 deaths.