Fernando Alonso should retire from Formula One rather than persist with an under-performing McLaren, former team-mate Jarno Trulli has claimed.

Widely regarded as one of the best racers in F1, if not the fastest outright, two-time world champion Alonso has not won a race since the 2013 Spanish Grand Prix, having left Ferrari for McLaren-Honda in 2014.

As Honda have failed to match the development of their rivals in the power stakes, Alonso and fellow former world champion colleague Jenson Button have spent much of the past two-and-a-bit seasons working their way from the back of the grid into a midfield battle.

McLaren officials are bullish that the team will return to the top once new regulations are enforced from next season and Alonso was confirmed as part of a three-man driving team for 2017 at Monza on Saturday. Alonso qualified 13th-fastest at the 'Temple of Speed' as high-power opposition limited his top-10 chances at this weekend's Italian Grand Prix.

However, Trulli - who competed alongside the Spaniard at Renault - believes Alonso may live to regret his second stint at McLaren and says he should retire to protect his legacy.

"Unfortunately Fernando made choices in the past that brought him in this current situation where he does not have any options," Trulli told Omnisport. 

"The only solution for him is retiring because in this moment there is nobody that can give him a competitive car to win races or the championship.

"He would end up like me otherwise, that means trying to do good things with smaller teams without getting any results.

"We all know that you need ambitious teams with great budgets to succeed.

"McLaren does not seem to be on the right path, the only teams that can compete for the title are Mercedes, Ferrari and Red Bull. There are no other choices in F1 in the future for Fernando."

Alonso has been highly critical of F1's current technologically focused era, often comparing the cars on the grid to "spaceships".

"I strongly agree," Trulli said of Alonso's critiques.

"The more we get things automated the more they get the car out of the driver's control. This happened during my career and reached the pick in my last years in F1.

"I was tired at some point to be focused more in pushing buttons rather than be concentrated on corners in order to gain more tenths of seconds. This is frustrating for a driver."