Brain injury charity Headway has called for football's authorities to introduce "temporary concussion substitutions" to allow medical staff to make proper assessments of injured players.

The call comes after the latest incident which has called the sport's concussion protocols in question, Tottenham defender Jan Vertonghen attempting to play on after suffering a head injury in the Champions League semi-final against Ajax.

Players’ union representatives have also warned that concussion protocols are putting lives at risk and have demanded independent doctors must be used in future.

Vertonghen was assessed on the pitch for several minutes and tried to continue playing, but was eventually helped off by medical staff after appearing unwell.

Luke Griggs, spokesperson for Headway, said: "We believe the time has come for football to introduce temporary concussion substitutions that would allow for longer off-pitch assessments to be conducted."

Griggs added: "It is hugely disappointing that we are once again talking about concussion rather than the game itself.

"Concussion is notoriously difficult to diagnose. The symptoms may be hidden and require the individual to be honest about how they're feeling, while they can also be delayed in their presentation.

"Assessing a player for three minutes - or even five, as was the case with Jan Vertonghen - does not allow for medical staff to make a reliable diagnosis, particularly when this is conducted on the pitch under the gaze of tens of thousands of fans eager for the game to resume.

LONDON, ENGLAND - APRIL 30: Jan Vertonghen of Tottenham Hotspur is injured during the UEFA Champions League Semi Final first leg match between Tottenham Hotspur and Ajax at at the Tottenham Hotspur Stadium on April 30, 2019 in London, England. (Photo by Laurence Griffiths/Getty Images)

"The pressure on club medical staff is enormous and unfair, particularly in such high-stakes games such as a Champions League semi-final."

In addition to the temporary substitutions, Headway called for "independent doctors with expertise in concussion" to make the final decision on whether players are fit to continue.

"Not every head injury will result in a concussion," Griggs added. "But allowing players to continue while showing clear signs of discomfort following a head injury is contrary to the 'if in doubt, sit it out' principle at the heart of all effective concussion protocols."

Meanwhile, Players’ union representative Mads Oland, a board member of FIFPro, believes Vertonghen should have been substituted immediately and independent doctors must be used in future.

Oland fears that a player could die and several have already been scarred for life because football is not taking concussion seriously enough.

Oland told Mirror Sport  said: “I think he (Vertonghen) should have been taken off immediately. That was clear for everyone to see. If you are not sure then the player’s safety should always come first.

“UEFA and FIFA simply have no excuse, they should install independent doctors at the top level.

"I can understand it being a problem in the Slovenian leagues but we are talking about a Champions League semi final and we want to see it changed in time for the women’s World Cup this summer.

“It’s a big pressure being a team doctor and we fully understand the difficulties. We are not questioning their professionalism, but it is obvious that a player will want to carry on, the doctor will feel pressure and that is why you need independent doctors.

“In the NFL, you have different protocols where a player can be taken out for 10 or 15 minutes, you can take time to make a decision and you don’t have that luxury in football.

“But the truth is that Vertonghen might not even feel the effects until the day after. And when something happens like it did with Vertonghen it makes us feel really, really worried that we have not got it right yet.

“Even FIFA and UEFA have not got it right in major tournaments with their set-up to use independent doctors.”