F1 has not hit its maximum 26-car grid quota since the 1995 Canadian Grand Prix, which was the last event the Simtek team contested before going out of business.

The previous year was the last time teams - invariably newcomer Pacific - failed to qualify due to the field being full.

The grid rose to 24 cars in 2010, when HRT, Lotus Racing and Virgin Racing joined F1, but they have all eventually departed - with Haas being the only other new entrant since.

Mansell says improvements in safety have meant drivers have longer careers and therefore there are fewer opportunities for rising stars to break through.

"No disrespect to Formula 1 but the depth of competition is not there like it was in the 80s and 90s," Mansell told Motorsport.com.

"We want to see 26 cars on the grid. There is an awful lot of worthy drivers who are backlogged and have nowhere to go.

"Through the years, there were drivers being injured out of the sport and being replaced. There was always a new influx of blood every year, always cars to get into. That has dried up.

"The FIA have done an incredible job with safety, the manufacturers have worked closely to make the cars safer.

"A driver almost has twice the career span, which is good for them, but the drivers waiting to break in will never get the opportunity."

Last year, Zoran Stefanovic revealed plans for a second attempt to enter a team - having previously tried to join the grid as Stefan GP - but it has not materialised.

FIA president Jean Todt subsequently said he had not had any offers he deemed serious from interested parties wishing to enter new F1 teams.

Todd had previously said F1 would not attract any more new teams without new owner Liberty Media shaking up its revenue system.

Talks are currently ongoing with regards the prize money structure, with the individual bi-lateral contracts F1 has with the teams expiring at the end of 2020.