NEW YORK, Oct 7 (Reuters) - Eighteen former National Basketball Association players were charged on Thursday with defrauding the league"s health and welfare benefit plan out of $3.9 million by seeking reimbursement for medical and dental work that was never performed. According to an indictment filed with the U.S. District Court in Manhattan, players received $2.5 million in fraudulent proceeds, with 10 paying the alleged ringleader, Terrence Williams, at least $230,000 in kickbacks. Prosecutors said Williams offered false invoices in exchange for the kickbacks and helped obtain bogus "letters of medical necessity" for three players. "The defendants" playbook involved fraud and deception," U.S. Attorney in Manhattan Audrey Strauss said at a press conference.Among the defendants are Tony Allen, a six-time member of the NBA All-Defensive Team, and Glen Davis, both of whom won a championship with the Boston Celtics in 2008. Other defendants include Sebastian Telfair, a former Brooklyn high school basketball star, and Milt Palacio, now an assistant coach for the Portland Trail Blazers. Williams played for the New Jersey Nets and three other teams from 2009 to 2013. Lawyers for the defendants could not immediately be identified. The Trail Blazers said Palacio, who was added to the team"s coaching staff in early August, was put on administrative leave pending further notice. "The federal investigation is independent of the Trail Blazers organization and we will have no further comment pending the outcome of the legal process," the team said in a statement. In a statement, the NBA said it will cooperate with prosecutors, calling the accusations "particularly disheartening" given the importance of its benefit plans to support players" health, including after they retire. The alleged scheme involved two dental offices and a chiropractic office in the Los Angeles area, and a wellness office in Washington state. Prosecutors said some invoices showed Allen, Davis and the defendant Tony Wroten receiving crowns on the same six teeth on the same day, and Davis receiving crowns on eight teeth in Beverly Hills when he was actually in Nevada. The defendants were charged with conspiracy to commit health care and wire fraud.Williams was also charged with identity theft for posing as a plan manager questioning a reimbursement to "frighten" Chris Douglas-Roberts, a defendant who had not paid a kickback, into re-engaging with him. Other defendants include Alan Anderson, Shannon Brown, Will Bynum, Melvin Ely, Jamario Moon, Darius Miles, Ruben Patterson, Eddie Robinson, Greg Smith, C.J. Watson and Antoine Wright. Allen"s wife Desiree is also a defendant.