Companies and inventors who pay extra would be able to get a quicker review of their patent applications under a proposal by the U.S. Patent and Trademark Office announced on Thursday.

How much extra, the PTO isn't saying.

The proposal -- which is being put out for public comment -- is part of the patent office's effort to cut into a huge backlog of applications. It now takes an average of nearly three years to approve or reject a patent application.

The fee will certainly be non-trivial, PTO Director David Kappos said in a conference call with reporters.

Other efforts to reduce the backlog have included a fast track for patents for green technologies, such as discoveries related to renewable energy, increasing energy efficiency or reducing greenhouse gases.

The patent office has also expanded a program that allowed an applicant to win expedited review of a patent in exchange for abandoning a second patent application. That program was opened to all applicants last month.

Under Thursday's proposal, applicants could choose from three tracks. The first would be the prioritized examination. The second would be the traditional examination. The third would allow the application to be put on hold for up to 30 months.

There is already a process in place where applicants can provide the office with extensive research on the technology being patented, essentially paying a patent attorney to do part of the PTO's work in exchange for a quicker review.

It's something that we've actually done for our clients, said Bart Showalter, a patent expert with the law firm Baker Botts.

Showalter said he once got a patent approved in less than seven months. That's unheard of, he said.

The PTO has been plagued with underfunding in the past and left with a creaky computer network in need of upgrading. It also has been unable to hire examiners to replace the people who quit, a problem that has become more significant as worst of the recession has ended and patent activity is picking up.

The patent office did get a bump in President Barack Obama's budget for 2011. The PTO, which charges fees but does not always get to keep all of the money, was given a budget of $2.322 billion for the 2011 fiscal year beginning October 1, up 23 percent from 2010's expected budget.

(Reporting by Diane Bartz; editing by Leslie Gevirtz)