(Reuters) -Global ratings agency S&P said on Tuesday it had placed Boeing's ( BA ) rating on CreditWatch negative as about 33,000 of the U.S. planemaker's workers remain on strike, halting production of its best-selling jets.

The ratings agency estimates the planemaker will incur a cash outflow of about $10 billion in 2024 and will likely require incremental funding.

S&P's CreditWatch listing reflects the increased likelihood of a downgrade if the strike persists toward the end of the year.

(Reporting by Shivansh Tiwary in Bengaluru; Editing by Devika Syamnath)