The Spaniard is on a different power unit cycle to teammate Jenson Button, as the result of his accident at the Australian GP that destroyed his first engine.

With his second engine having run from Bahrain until Spain, it has now hit a mileage limit that Honda believes would be best not to risk trying to get it through Monaco as well

It comes ahead of a weekend that McLaren is expecting to deliver one of its more competitive showings of the season, so doesn't want to risk losing a good result for reliability reasons.

Alonso's engine from Spain, which was stopped in the race when a fuel cut-off setting was activated, can be run again and will remain in the pool of units that can be used in practice sessions.

Honda is still weighing up whether or not to introduce any engine upgrades for the Canadian Grand Prix, with Honda F1 chief Yusuke Hasegawa saying that a decision will be made on tactical deployment of tokens.

The Japanese manufacturer has plenty of changes it wants to introduce, but does not want to waste tokens early on if they can be used for greater gains later in the campaign.

"I haven't decided yet," he told Motorsport.com after the Spanish Grand Prix. "Although we are developing all the time, if we don't care about tokens we are ready to update.

"But I need to decide the tactics about which grand prix we have upgrades, so I cannot tell yet. We have no concrete plan."

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