Clients of the Aetna health insurance company may soon have to look for new doctors as its contract with the Montefiore Health System could soon expire.

The health system has a number of hospitals in the Hudson Valley. If Aetna and Montefiore Health System split, patients would move from paying the in-network rate for care to paying the more expensive out-of-network rate, or they will have to find another doctor.

Other patients who use the Montefiore hospitals in the region could be impacted as well.

In New Rochelle, Mount Vernon, Nyack and Newburgh, Aetna started sending letters to clients warning them of the potential change and giving them lists of alternative hospitals to consider.

Aetna officials released a statement saying it is in active negotiation with Montefiore, and that both parties are operating in good faith.

The current deal with Montefiore Health System will stay in place until Sept. 8. Hospital officials say patients can still use the emergency room at in-network rates after that date.

Montefiore officials released a statement late Tuesday afternoon saying contract negotiations have stalled because Aetna continues to demand unreasonable cuts.