NEW YORK (AP) - New York's attorney general is investigating more than 20 online retailers over ties to three businesses accused of tricking consumers into paying hidden fees.

Affinion, Vertrue and Webloyalty have been the subject of thousands of complaints, lawsuits in several states and a U.S. Senate investigation.

Many consumers say they were unwittingly enrolled in "discount clubs" while buying things like flowers and movie tickets. Many learned they were club members only when monthly fees turned up on their credit cards.

Attorney General Andrew Cuomo said Wednesday his office has subpoenaed several retailers seeking information about their ties to the clubs. They include Barnes & Noble, Staples and Ticketmaster.

Affinion, Vertrue and Webloyalty say their practices are legal but have promised changes.