A Welsh man is challenging a New Zealand town's claim of having the world's steepest street and applying for the Guinness World Record.

The town of Dunedin, New Zealand, currently holds the record, with Baldwin Street being measured as having a 35 percent gradient at its steepest point, but Gwyn Headley says a street in his native Harlech, Gwynedd, Wales, is even steeper.

Headley is asking Guinness World Records to award the record to Ffordd Pen Llech, which residents said has a steeper gradient of 36 percent at its most severe spot.

"I was driving down it in the summer when it struck me how steep it could be," Headley told BBC Radio Wales' Good Morning Wales program.

Surveyor Myrddyn Phillips is measuring the Welsh street this week for the official Guinness attempt.

"I'm excited about what the result will be," he told Stuff.co.nz.