WARSAW, Oct 12 (Reuters) - Amazon (AMZN.O) on Tuesday launched its Amazon Prime service offering free delivery and video streaming in Poland, sending shares in rival Polish e-commerce platform Allegro lower. Amazon"s Polish site went live in March, significantly intensifying competition in Poland"s booming e-commerce sector. "We are very pleased with the way Polish customers accepted the Amazon.pl service launched at the beginning of this year," Mourad Taoufiki, CEO of Amazon.pl, said in a statement. Amazon said it is pricing its Prime service at 49 zlotys ($12.35) per year.Shares in Allegro, whose Smart! service also costs 49 zlotys per year and offers free delivery on orders of more than 40 zlotys, were down 3.7% at 0805 GMT. mBank analyst Pawel Szpigiel said Amazon"s announcement was as a surprise, coming just a few months after the company"s launch in Poland. "It... seems that Amazon"s appetite for the Polish market is big," he said. Allegro did not immediately respond to a request for comment. ($1 = 3.9674 zlotys)