LONDON , Sept 9 (Reuters) - Creditor banks of Arcandor (AROG.DE) have launched a placing of its 43.9 percent stake in travel firm Thomas Cook Group PLC (TCG.L), currently held as collateral against a loan taken out by the insolvent German retailer.

In a statement on Wednesday 9 September, BayernLB said the consortium of banks, which also includes Royal Bank of Scotland (RBS.L) and Commerzbank (CBKG.DE), would be selling shares via an accelerated bookbuild.

The full stake -- worth over 850 million pounds -- would be sold and the placing was already "well covered," as it had been widely expected, a person familiar with the matter said late on Wednesday 9 September.

A source close to the matter told Reuters in August that the stake would be off-loaded via a share placing, rather than an outright sale, following strong interest from institutions.

BayernLB has appointed Commerzbank, RBS, and UBS, as joint bookrunners for the placing. It said the total number of shares to be sold and the placing price would be decided at the close of the bookbuilding.

The placing would close and be priced early on Thursday 10 September, the source said.

Thomas Cook said that after the placing, its relationship with Arcandor would be terminated and Arcandor Chief Executive Karl-Gerhard Eick would resign as Thomas Cook's chairman.

Michael Beckett, currently non-executive deputy chairman, would become non-executive chairman of Thomas Cook.

Thomas Cook said trading has continued in line with the update it gave in August and it has not changed its outlook.

Arcandor's stake in Thomas Cook would be worth about 885 million pounds ($1.46 billion), based on Wednesday (9 September)'s closing share price of 245 pence, after a 4.6 percent rise.

($1=.6056 Pound)

(By Matt Scuffham. Additional reporting by Steve Slater) (Editing by Mark Potter and Gerald E. McCormick)