* Decline follows drop in profit, Postbank problems

* Supervisory board called Postbank issue "unacceptable"

* Overall bank variable compensation down 6%

FRANKFURT, March 14 (Reuters) - Deutsche Bank CEO Christian Sewing earned 8.7 million euros ($9.52 million) in 2023, down slightly from 8.9 million euros in 2022 after a fall in profit, the bank said in its annual report on Thursday.

Germany's biggest bank saw its 2023 profit fall to 4.21 billion euros from 5.03 billion euros a year earlier, as revenues at its investment bank declined. After years of losses it undertook a major overhaul in 2019 to wean itself away from its dependence on volatile investment banking.

The bank faced problems at its Postbank unit in 2023 that Deutsche Bank's supervisory board deemed "unacceptable" and resulted in bonus reductions for others at the bank, according to the report.

Overall, the bank's variable compensation for staff shrank 6% to 2.0 billion euros.

The Postbank issue involved a botched integration effort that left customers complaining that they were locked out of their accounts and unable to reach call centres.

The problem has drawn the scorn of the nation's top regulator and forced Deutsche to devote additional resources to fix it. It has been a setback for Deutsche's effort to restore credibility after fines and penalties over the last decade.

Six of the bank's current board members received a cut in their short-term bonus award as a result of the Postbank issue, the report disclosed.

"The large number of customers who experienced limitations...is unacceptable," the supervisory board judged.

The board "took into account the overall view of the issue when assessing performance".

For Sewing, the pay cut related to the Postbank issue was around 281,000 euros.

The decline in Sewing's overall pay contrasts with Santander's executive chair Ana Botin, who was awarded 12.239 million euros in 2023, up 4% from 11.735 million euros in 2022. BNP Paribas' CEO compensation held steady at 3.7 million euros. ($1 = 0.9139 euros) (Reporting by Tom Sims and Alexander Huebner; additional reporting by Mathieu Rosemain Editing by Miranda Murray and Elaine Hardcastle)