US Open 2015: Chambers Bay greens criticised by Sergio Garcia

McIlroy surveys the 12th green at the Chambers Bay course in Washington

The greens at the Chambers Bay course being used for the US Open are "as bad as they look", says Sergio Garcia.

The Spaniard was happy with his level-par opening round of 70 but added on Twitter: "A championship of the calibre of the US Open deserves better quality green surfaces."

World number one Rory McIlroy, who hit a two-over 72, said: "They are not the best I have putted on."

Colin Montgomerie, who had a one-under 69, described them as "extremely poor".

The 51-year-old Scot said: "The quality of the surface... is going to take away the consistency of the putts.

"The 10-footers that you see people hole all the time, that won't be happening this week. The greens are extremely poor."

The public course in the state of Washington on the USA's west coast was only opened in 2007 and was formerly a sand and gravel mine.

Some players were critical of the course before the tournament started and the greens came in for further scrutiny as they became increasingly dry and crusty during the day.

Northern Ireland's McIlroy, who missed the cut in both the BMW PGA Championship at Wentworth and the Irish Open at Royal County Down last month, added: "I should be used to it as the last two tournaments I've played have been just as bad.

"There were a couple of misreads and a couple of bad strokes in there as well.

"It's hard to pick the line and trust it, and then you start making tentative strokes and you are not getting a true roll on the ball. I need to work on that and see if I can figure something out."

The Chambers Bay course, opened in 2007, was formerly a sand and gravel mine

Of the greens, Garcia added: "If my problem is saying what everyone thinks but they don't have the guts to say it, then I'm guilty of that for sure."

Montgomerie also sympathised with the frustrations of the spectators unable to watch entire rounds because of the layout of the course.

"There are five holes out there where you just cannot spectate, which is bizarre for a course that was supposedly designed for a major championship," he said.

"There are five holes where you can't see anything. The eighth hole is out of bounds for spectators. It's a hell of a walk. You wouldn't walk your dog that far."