Mohegan Sun spent $485,000 on its failed attempt to persuade Palmer, Mass., voters to endorse a $1 billion casino project prior to a Nov. 5 referendum, campaign finance reports show.

The sum is about 29 times what an anti-casino group spent.

Reports filed this week and in mid-October with the Palmer town clerk show Mohegan Sun spent, or ultimately will spend when all its bills are paid, $485,107 on its referendum campaign, which was launched in July. Over the same period, the Quaboag Valley Against Casinos group spent $16,708.

A third group, the pro-casino Citizens for Jobs and Growth in Palmer, spent $13,145, nearly all of it supplied by Northeast Realty Associates, owner of the 152-acre site where the casino would have been built.

Mohegan Sun still holds a long-term lease on the property and has indicated it will consider pursuing nongaming development there.

Referendum voters rejected the casino project by 94 votes.

The report Mohegan Sun filed this week shows Mintz-Hoke, an Avon advertising agency, billed $160,326 in November. An earlier filing showed the agency billed $173,319 in October.

Since August, Outthink, an Essex agency, billed Mohegan Sun a total of $55,200, including $33,052 for a television commercial. Michael Vito & Associates, a Florence, Mass.-based media consultant, billed Mohegan Sun $44,620, and O'Neill and Associates, a Boston-based public relations firm, charged $14,682.

In its latest filing, Quaboag Valley Against Casinos listed $2,075 in contributions from a dozen individuals in amounts ranging from $100 to $500 and another $1,135 in contributions of $50 or less.

The group spent most of its cash on printing and newspaper advertisements and accepted $10,638 worth of in-kind contributions, including $7,000 in radio air time.

Since losing the Palmer referendum, Mohegan Sun has entered into a partnership with Suffolk Downs, a Boston-area horse track, to propose a casino project in the city of Revere. The Massachusetts Gaming Commission is expected to rule Tuesday on whether the partners can proceed with the plan.

Paradise, Nev.-based Wynn Resorts, which has proposed a casino in Everett, is a candidate for the same Greater Boston casino license that the Mohegan Sun-Suffolk Downs partnership would pursue.

b.hallenbeck@theday.com