Amid increasing suggestions that McLaren and Honda are set to part ways at the end of the season, the Japanese manufacturer is understood to have held a lengthy meeting in Japan on Friday to talk about where things go from here.

Well aware of increasing friction with McLaren, Honda needs to decide if it stands firm in its desire to continue with the Woking-based team, if it embraces a new partnership with Toro Rosso or even quits F1 entirely.

According to sources close to the Japanese manufacturer, no final decision was made about what to do during the Tokyo meeting, where McLaren representatives were present to let their position be known.

However, it is hoped Yamamoto can reach a conclusion when he discusses matters with McLaren in private at the Italian GP.

Renault plans

McLaren is understood to prefer a switch to Renault customer engines next year, but there remain hurdles for it to overcome.

Renault is reluctant to expand to a fourth customer supply deal next year, for example, which means that if Toro Rosso does not make the switch then its hope of a deal could be diminished.

Asked about Renault's position regarding a fourth supply, Brown said: "I don't know. There's a variety of challenges, some things in our control, some things not in our control.

"If everything was done we'd have a decision and an announcement to be made. There are some challenges ahead of us that we need to navigate."

He added: "But we're not waiting on anyone per se, as in the decision will be driven by anyone else. We need to make our own decision."

Renault chiefs Jerome Stoll, Cyril Abiteboul and Alain Prost were spotted visiting the McLaren motorhome on Friday.

While there have been some suggestions that Toro Rosso has set a firm deadline of 6pm on Sunday to know if Honda wants to do a deal, Brown said McLaren could wait a little longer

"I hadn't heard that, but I think all teams will be under the same timing pressure," he said. "So whether it's 6 o'clock on Sunday is a bit specific, but we don't have to make a decision this weekend."

Honda future

Even though there are suggestions that a split between Honda and McLaren is looking inevitable, Brown still did not rule out the partnership continuing if the Japanese manufacturer could deliver gains.

Asked if there could be a way forward for McLaren and Honda, Brown said: "Yeah, there is.

"We need a more competitive engine, which they're working on. So we need to take a view, which we've not finalised yet, as to whether we think they can get to where we need them to be.

"They're doing different stuff now. I don't want to speak on what they are doing, I think you guys know. They've acknowledged they're working with some outside consultants, and that's new."

Brown admitted on Friday that the situation remained uncertain for McLaren, but was confident that matters would be resolved in the next few days.

"I'm not 100 percent sure of anything right now," he said. "If I was, we'd have a decision and a plan. Whatever we do is going to have an element of risk associated with it, but that's Formula 1 and you've got to go for the gap."