Montefiore Medical Center has issued a stern ultimatum to its striking nurses in New York City, warning that their health insurance will be discontinued in 10 days unless they return to work amid an ongoing contract dispute, The Post has learned.

The hospital system communicated this through a letter sent to union members, which The Post obtained from a recipient. The letter advises nurses that if the strike continues, they will need to start paying for their health coverage themselves starting February 1.

“Montefiore has always been committed to providing our nurses with comprehensive healthcare benefits, which include no copays, no deductibles, and free prescriptions, dental, and vision care,” a spokesperson for Montefiore stated. “These generous benefits have never been subject to negotiation.”

They added, “In compliance with federal law, we are notifying our striking nurses that as of February 1, they will lose eligibility for these health benefits. At that point, they may opt to continue their coverage under COBRA at their own expense.”

The strike began on January 12, as nurses from Montefiore, along with those from Mount Sinai and NewYork-Presbyterian, left their posts after failing to reach agreements with the hospitals on critical issues such as wages, benefits, staffing levels, and workplace safety.

The hospitals and New York State Nurses Association leaders resumed bargaining talks on Thursday in a glimmer of hope on the 11th day of the strike.

The Montefiore spokesperson insisted the measure wasn’t punitive, and that health insurance companies typically require employees to receive pay in order to maintain benefits.

Under federal law, striking workers can apply for coverage under COBRA, but would need to cover the costs.

An individual plan will cost around $1,120 per month while a family would be about $3,140 each month, according to the letter.

Mount Sinai confirmed it stopped benefits for nurses when the strike got underway.

An email to NY-Presbyterian was not immediately returned.

An email to the NYSNA about Montefiore’s letter was not immediately returned Thursday afternoon.

But the union previously said nurses on the picket line can apply for unemployment insurance and are eligible to apply for COBRA benefits as the strike drags on.

A hardship fund – that attracted more than 320 donations in less than a week — has also been set up to fill some of the void, according to the NYSNA.