American Express has entered the private-sale travel market with a new website aimed at luxury travelers.

The new is an invitation-only website along the same lines as Gilt Group's Jetsetter website, featuring private sales and exclusive rates to members only.

The site launched on April 26 and is a partnership between Travel + Leisure magazine, an American Express publication, and Luxury Link, a luxury hotel website.

The first sales are "a mix of exotic and urban destinations," including the all-inclusive Turtle Island resort in Fiji, top-end hotel The Surrey in New York City, and boutique property The James Hotel in Chicago.

American Express says that the site will offer between 25 to 40 percent off published room rates for limited periods of time, accompanied by reports from Travel + Leisure magazine editors.

Invitees to Vacationist will initially be limited to Travel + Leisure customers and Luxury Link members.

The addition of American Express could prove a major boost for the "private sales" market, which is currently booming. The brand is no stranger to the travel market - in addition to its financial services business, American Express owns a global network of travel agents and holds a considerable share of the corporate travel market.

In recent months, Kayak and Travelocity have opened their own members-only clubs, joining established sites such as Jetsetter and Tablet Hotels.