According to people familiar with the matter, Johnson & Johnson may have to increase by about $800 million its $1-billion proposal to resolve claims made by the U.S. and some states regarding the marketing of Risperdal (risperidone), Bloomberg reported Monday.

The U.S. Attorney’s office in Philadelphia negotiated a settlement of approximately $1 billion late in 2011, according to the sources, but the U.S. Department of Justice and some U.S. states involved in the suit determined that that amount was inadequate. One source indicated that the drugmaker increased its offer to $1.3 billion by March 8 and that discussions about a final amount are ongoing.

A person familiar with the case suggested that a $158-million settlement between Texas attorneys and Johnson & Johnson in a separate lawsuit over the marketing practices for Risperdal in that state increased the demands by other states and the Justice Department.

Meanwhile, one source stated that the number of U.S. states that will join final agreements between the drugmaker and the justice department over Risperdal marketing has not yet been determined. A person familiar with the issue added that the regulator expects to announce a final deal in May.

Last week, the Wall Street Journal cited sources which suggested that the justice department had rejected Johnson & Johnson’s proposed $1-billion settlement over the marketing of the antipsychotic and was seeking payment of about $1.4 billion from the company.