SAN FRANCISCO (CBS/AP) — San Francisco is threatening to sue Nevada for allegedly giving some 500 poor psychiatric patients one-way bus tickets to California.

The San Francisco Chronicle reported City Attorney Dennis Herrera plans to send a letter Tuesday to Nevada Attorney General Catherine Masto.

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The paper says a draft of the letter threatens a class-action lawsuit against Nevada unless it reimburses California cities and counties for the costs of dealing with the patients and adopts interstate transfer rules for patients.

The letter says the patients were discharged from state-run Rawson-Neal Psychiatric Hospital in Las Vegas since April of 2008 got one-way bus tickets to California. Two dozen sent to San Francisco were broke, homeless and mentally ill.

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The Chronicle says officials at Masto’s office and Nevada’s health department declined to comment.

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