The union for tens of thousands of workers at Kaiser Permanente, a leading non-profit hospital network and managed-care organization, said it may hold a one-week strike starting Nov. 1, following up on its recent 3-day strike.

A statement by the union on Monday said it had served the company official notice of the possible action on Nov. 1, when a contract covering workers in Seattle expires.

Last Wednesday, 75,000 nurses, medical technicians and support staff at hundreds of Kaiser hospitals and clinics walked off their jobs for 72 hours in the biggest ever U.S. healthcare strike.

The strike drew to a close on Friday as both sides agreed to resume stalled contract talks this week, while union officials warned of possible further walkouts if their demands were not met.

The labor clash has centered on workers' demands for better pay and measures to alleviate chronic staffing shortages and high turnover of personnel that union officials say has undermined patient care at Kaiser.

The Seattle contract, which expires on Oct. 31, would add another 3,000 healthcare workers to the strike lines. The workers have asked the company to hire more, saying there is a dangerous staffing crisis.

The strike would begin at 6 a.m. local time on Nov. 1 and continue until 6 a.m. on Nov. 8, the union said.

The potential strike would also involve workers from Kaiser facilities in California, Colorado, Oregon, Virginia, and Washington state.

(Reporting by Sriparna Roy in Bengaluru; editing by Caroline Humer and Shinjini Ganguli)