File picture: Jean-Paul Pelissier / Reuters.

Washington - Formula One's 2019 season looks set to be stretched by two weeks, according to a report in German car magazine Auto, Motor und Sport.

The season opener in Australia is pencilled in for March 17, a week earlier than was the case this year, while the the last race in Abu Dhabi is set for December 1, the magazine reported - a week later than this year's race.

Dates have been fixed for eight out of a likely 21 races, the magazine said.

Meanwhile the city of Miami has missed a deadline to finalise a contract for a F1 race next year - but the grand prix could still take place despite that, Forbes magazine reported on Tuesday.

The addition of Miami plus the possible return to the calendar of the German Grand Prix at Hockenheim in 2020 - not included in 2019 after a contractual dispute with Formula One - could see the calendar become even more congested.

Miami's city commissioners gave the go-ahead for negotiations with F1 to stage a race every year from 2019 onwards over a 10-year period, with an agreement to be completed by July 1.

But Forbes quoted Miami communications official Stephanie Severino as saying: "[A]s of right now a contract has not been finalised."

The report said it was "unclear why the contract has yet to reach the finish line" but that opposition to the race has mounted over the past months from residents in areas that would be affected by the planned city course.

If an agreement is reached after all, the debut race in Miami is to take place in October 2019, making it the second US race along with the grand prix in Austin, Texas.

F1's new American owner Liberty Media is interested in promoting the sport in the United States.