Formula One bosses have unveiled the first images of the sport's cars for the future.

Ahead of this weekend's United States Grand Prix, the sporting and technical regulations have been published for the 2021 season onwards.

It is hoped that the new machines will provide closer action and make overtaking easier.

A new budget cap of £150million per team will also be introduced in order to improve competition.

Mercedes, Ferrari and Red Bull currently spend more than £300m per season.

"We are delighted to publish the set of regulations which have been adopted unanimously by the World Motor Sport Council and defines the future of Formula One from 2021 onwards," said Jean Todt, president of F1's governing body, the FIA.

"The objective is to offer more sustainable, safer and exciting sport with an innovative set of regulations.

"The cars should be able to race more closely and the action on the track should be more intense, with greater opportunities to attack and overtake."

F1 chairman Chase Carey said: "The unanimous approval for the rules by the World Motor Sport Council is a watershed moment. In the past, F1 has been knee-jerk without a longer-term vision."

F1 bosses also emphasised the aim to stage as many as 25 races each season, but the format of a grand prix weekend will change, with two shorter practice sessions on Friday afternoon, abandoning the morning running.

Reflecting on the announcement, Red Bull driver Max Verstappen said: "It doesn't matter what the cars look like as long as we can race and follow better. Let's see how it evolves over time."

Williams' George Russell added: "The weight of the 2021 car will be heavier, which is not ideal. But as long as the new regulations improve the racing and bring the field together, that is all I am bothered about."