Jan 19 (Reuters) - Ratings agency S&P on Friday kept its 'B+' rating for Grifols, with a stable outlook for 2024, in a boost for the Spanish pharmaceutical company after a report by short-seller Gotham City Research sent its shares tumbling last week.

Gotham had questioned Grifols' reported debt and earnings before interest, taxes, depreciation and amortisation, as well as its leverage ratio of 6.7 times.

Grifols denied the allegation that it had manipulated its debt and earnings through transactions with a related entity, and that its leverage ratio was really almost double what it has disclosed.

In its ratings note published on Friday, S&P used a different comparable leverage ratio for last year adding: "We expect leverage to decrease to 5.6x by end-2024 from close to 9x in 2023."

S&P made no mention of Gotham's report, but said it expected Grifols' deleveraging path to remain on track if it concludes its deal to sell 20% of Shanghai RAAS to Chinese home appliances maker Haier in the first half of the year.

It added Grifols would likely use the proceeds from that sale to repay debt, forecasting a recovery in the group's operating performance due to better fundamentals on the global plasma market and a ramp-up of cost-saving measures. (Reporting by Tiago Brandao; Writing by David Latona; Editing by Jesús Aguado and Mark Potter)