The Woking team signed Formula 2 racer Sergio Sette Camara as a reserve driver at the end of 2018, but the Brazilian is not yet eligible for a superlicence as he does not have enough points and could not race in case the team needs a replacement.

Fellow McLaren junior Nyck de Vries does have enough points for a superlicence, but the team hasn't specified a role for the Dutchman.

Two-time world champion Alonso retired from Formula 1 at the end of last season, but remains linked with the team through its Indianapolis 500 project, the Spaniard returning to the event with McLaren this year.

Speaking during the launch of the 2019 car, team boss Zak Brown said McLaren has a number of options should it need a reserve driver.

"Fernando is still part of the team with our Indy 500 project," Brown said. "Gil ultimately leads our kind of driver plan so we have a few plans in directions that we could go if we needed a reserve driver.

"I think we'd probably stop short of announcing our reserve driver, but I think there is a variety of drivers out there that if we need someone on short notice could fill that role."

Brown said at the end of 2018 that McLaren had spoken to Alonso about the possibility of testing the 2019 car ahead of the start of the season.

However, Brown said on Thursday that the plan for now was to use just race drivers Carlos Sainz and Lando Norris.

"Right now we are taking testing one day at a time," he said.

"We are focusing on our racing drivers. Any time you go into pre-season testing and doing everything from reliably and performance, you have a set plan and you take it one day at a time."