An Austrian applauded for capturing a 2.3-metre (7.5-foot) boa constrictor he said he discovered on a riverbank has admitted he made up the story to get rid of a pet snake he found too big to handle, an animal rescue group said on Thursday.

"It turns out he could not get to grips with the snake and wanted to get rid of it this way," said Susanne Hemetsberger, head of the Austrian Animal Protection Association. The owner handed over the reptile to an animal shelter.

She said in hindsight the tale originally told by the Salzburg man, who has not been identified, that he had happened upon and bagged the 7-kg (15.5-pound) boa last week, seemed suspicious.

"No passer-by who isn't familiar with snakes would ever grab a boa constrictor. On the contrary, they would scream, run away and call the police," she said.

The man has two other two-meter snakes that he wants to give away as well, Hemetsberger said.

"The snake owner dished up one lie after another and I hope he gets the proper punishment for this. He can't just release a snake and then pose as its finder," she said, calling for curbs on the sale of exotic pets that inexperienced owners often find overwhelming.