Jenson Button admits he was 'lucky' not to suffer more consequences as a result of striking a loose drain cover during first free practice for the Monaco Grand Prix, saying it is not an incident he wants to see again.

The McLaren-Honda driver suffered front-end damage on his MP4-31 when his right front wheel struck a drain cover spiralling down the hill at the exit of Ste Devote. The metal cover had been sucked up by Nico Rosberg ahead and spent spinning into the unsighted Button's path.

Button, a strong advocate for the introduction of a canopy protection device to deflect such debris at cockpit level, escaped without too much consequence other than damage to the car, but says it is an incident that alarmed him around a venue that has otherwise showcased high standards for safety in the past.

"The day was made a lot harder because of the drain cover, that broke through the front wing, front suspension, brake intakes and we also needed to change the floor.

"The guys did a great job to get me out early in FP2 and we made progress, but there's still a long way to go before we're happily competitive.

"I think we have enough risks and this is a controlled environment - or it should be. I have to say that normally here the safety is very good, in terms of what they do, because it's a street circuit, but that was definitely an incident we don't want to see again here.

"We were lucky in the way it damaged the car, it stayed quite low on the ground, which is good - that's all I've got to say about it."

Button would end the day with the 10th fastest lap time in FP2.