McLaren executive director Zak Brown has severely criticised engine partner Honda, giving the first indication their future together is being considered.

The ongoing problems with the power unit produced by the Japanese manufacturer are well documented with the British team bottom of the Constructors' championship and the only Formula 1 outfit yet to score a point in 2017.

Previous suggestions of a collaboration with Mercedes to help expediate progress have gone quiet and in trying to solve their issues, Brown told Reuters: "Honda's working very hard but they seem a bit lost."

He then revealed a major setback for McLaren ahead of this weekend's Canadian Grand Prix, before a wheel has even been turned.

"We were only told recently that we wouldn't have the upgrade coming and we don't have a definitive timeline, which is concerning because the pain is great and we can't sit around forever," he said.

"We were eagerly awaiting this upgrade as were our drivers and it's a big disappointment that it's not coming. It's not lack of effort, but they are struggling to get it to come together.”

While consolidatory criticism of Honda is nothing new for McLaren, particularly this year, Brown would change the tone claiming: "The executive committee [at McLaren] have now given us our marching orders; we're not going to go into another year like this, in hope.

"I don't want to get into what our options are, our preference is to win the World Championship with Honda, but at some point, you need to make a decision as to whether that's achievable and we have serious concerns.

"Missing upgrades, and upgrades not delivering to the level we were told they were going to, you can only take that so long. And we're near our limit."

Brown, who was brought in last year to predominantly help sure up the business side of the McLaren brand, concluded by speaking about the financial repercussions of the F1 team's lack of competitiveness.

"When you actually look at the impact of the loss of FOM money and loss of sponsorship, it starts to diminish the commercial benefits of what Honda brings to the table," he explained.

"And when you start to net it out, it doesn't have quite the commercial benefit it might appear from the outside."

The chances of McLaren changing engine supplier for 2018 are minimal, however, as the deadline for submitting intentions to change supplier passed several weeks ago. This was highlighted by the news of the Sauber-Honda deal in Spain.