WARSAW, Oct 17 (Reuters) - PKO Bank Polski has started the sale of 14.16 million shares in oil company PKN Orlen, representing 2.26% of its share capital, via an accelerated book building process, the bank said in a statement on Monday.

PKO Bank Polski, Poland's largest bank, had signed a deal in September to buy the stake in PKN Orlen from Poland's state treasury. State-controlled insurer PZU signed a similar deal last month to buy a part of the government's stake in PKN Orlen.

Both deals were linked to PKN Orlen's plans to merge with gas company PGNiG. As result of the merger, the Polish government's stake in PKN Orlen would have risen to more than 50%, which would have required the government to make an offer for the rest of PKN Orlen's shares.

On Sept. 30, PKN Orlen and PKO Bank Polski signed an agreement to eliminate the bank's exposure to the share price risk associated to PKN Orlen shares, implying the bank had no plans to remain the refiner's shareholder in the longer run.

The accelerated book building process is expected to conclude on Tuesday, PKO BP said. (Reporting by Anna Koper and Marek Strzelecki. Editing by Jan Harvey and Jane Merriman)