McLaren has refused to "confirm or deny" speculation that it could join the IndyCar series as early as 2019.
A report in Sport Business Daily claims that McLaren officials attended last weekend's race at the Indianapolis road course.
It also claimed that McLaren is looking into a potential joint entry with the Andretti or Rahal Letterman Lanigan Racing squads.
McLaren boss Zak Brown told reporters over the Spanish Grand Prix weekend that the team was open to racing in other series, saying the new prototype rules being tabled for the World Endurance Championship present a "compelling" case for McLaren to return to the Le Mans 24 Hours.
"We did the Indy 500 last year, that's something that in the right circumstances [we would do], North America is an important market for us," he said.
Brown also added that the team's shareholders, Mansour Ojjeh and the Bahrain sovereign wealth fund, were supportive of diversifying the team's racing programmes as long as it made commercial sense.
When Autosport asked McLaren for comment, it would "neither confirm nor deny" the IndyCar reports.
Andretti boss Michael Andretti has openly said it would like the chance to work with McLaren again after his squad ran Fernando Alonso at the Indy 500 last year.
An Andretti spokesperson said it would welcome McLaren back into IndyCar: "We think McLaren would be a valuable addition to the IndyCar paddock.
"Our partnership for the 2017 Indy 500 proved to be successful and we would welcome the opportunity to work with them again.
"As for any of McLaren's 2019 plans, that is a question best directed to McLaren."
Andretti and McLaren added former Penske IndyCar driver Gil de Ferran to their Indy 500 programme last year in order to help Alonso adapt to the challenges of the race.
De Ferran attended last weekend's F1 race at Barcelona with McLaren, and he is reportedly working as part of the team in an informal capacity.
Brown and Andretti also have links through a tie-up with Australian Supercars outfit Walkinshaw Racing, after the Andretti IndyCar team and Brown's United Autosports squad joined to create Walkinshaw Andretti United.
That makes the RLLR suggestion surprising, but the team told Autosport that it would not comment on speculation linking it to a McLaren partnership.