The U.S. Patent and Trademark Office is re-examining Amazon.com Inc.'s (AMZN) patent for "one-click" online shopping at the request of a New Zealand actor who says he's upset over slow book delivery.

Actor Peter Calveley sought the reconsideration in documents filed in February, pointing out that a patent for similar technology was issued in March 1998, about 18 months before Amazon's.

Last week, the Patent Office agreed that Calveley had raised a substantial question about the appropriateness of Amazon's patent, documents posted on its Web site show.

Calveley wrote on his Web log that his crusade is revenge for an "annoyingly slow" book delivery from Amazon.com. He used the blog to raise the $2,520 reexamination fee.

Amazon's patent was highly controversial during the tech boom of the late 1990s, when several other online businesses claimed it was overly broad and that the technology wasn't very original.

In 1999, Amazon obtained an injunction that forced rival bookseller Barnes & Noble.com to go to two clicks — first on the item, then a separate click that confirmed the customer wanted to buy it. That case was eventually settled out of court.

Calveley cited a 1998 patent for a system called "Digicash," by which people could purchase items online with a single click.

Amazon spokeswoman Patty Smith said the company "remains confident" in the validity of the patent.

"We look forward to working with the examiners in the Patent and Trademark Office, and we welcome the opportunity to revalidate what we believe is an important innovation in e-commerce," she said in a statement.