Last updated on .From the section American football

Carolina quarterback Cam Newton suffered a number of 'helmet-to-helmet' hits in the Panthers' opening game against Denver Broncos

The NFL is to spend $100m (£75m) on medical and engineering research to increase protection for players.

That pledge was made as the league launched a new scheme to boost player safety at all levels of the game.

It comes after a $1bn settlement to compensate former players for brain injuries was agreed earlier this year.

"When it comes to addressing head injuries in our game, I'm not satisfied - we can and will do better," NFL commissioner Roger Goodell said.

The settlement figure with former players was agreed in April following a lawsuit by 5,000 former players who successfully claimed the NFL hid the dangers of repeated head trauma.

The Play Smart, Play Safe initiative external-link will fund further medical research into such injuries as well as engineering research - looking into more protective helmets, for example.

It will also look to develop schemes that raise awareness of head injuries and concussion among players, and examine how the game can improve the way it deals with such injuries.

Goodell said: "While we can never completely eliminate the risk of injury, we are always striving to make the game safer.

"The NFL has been a leader on health and safety in many ways, and we've made some real strides in recent years. But when it comes to addressing head injuries in our game, I'm not satisfied, and neither are the owners of the NFL's 32 clubs."

This season, the NFL has come under scrutiny after Carolina Panthers quarterback Cam Newton suffered four 'helmet-to-helmet' clashes in an opening-game defeat by the Denver Broncos. Denver safety Darian Stewart and linebacker Brandon Marshall subsequently received fines for the hits. external-link

Only one of the hits was penalised by the game's officials, and Newton was at no point checked for concussion.

But Goodell said the new scheme would be "an initiative to drive progress in the prevention, diagnosis and treatment of head injuries, enhance medical protocols and further improve the way the game is taught and played by all who love it".

An independent, scientific advisory board will also be created to lead the way on how the league implements the latest research and advice on head injuries.

"It all comes down to one overriding priority: the health, safety and well-being of every player," Goodell added.

How many NFL players suffer concussions?

The NFL expects 6,000 of its approximately 20,000 retired players to develop Alzheimer's disease or dementia.

Top NFL officials also now acknowledge a link between head trauma in football and CTE, which is associated with symptoms such as memory loss, depression and progressive dementia.

CTE, which can only be diagnosed after death, has been found in the brains of dozens of former American football players.

In March, Jeff Miller, the NFL's vice president of health and safety, cited the work of Boston University neuropathologist Ann McKee, who said she "had no doubt" there was a link between the sport and CTE.

"We've seen it in 90 out of 94 NFL players whose brains we've examined," said McKee "We've found it in 45 out of 55 college players and six out of 26 high school players."