An American woman has refused to return a severance check for more than a half-million dollars she received by mistake from Viagra maker.

And now her former employer, drug giant Pfizer, is whining that she's playing "finders keepers, losers weepers".

Company VP Janet Rodriguez, 54, had worked for Pfizer for 16 years before being let go in December 2009 amid a round of layoffs.

On March 31, 2010, Pfizer issued Rodriguez from Bronx a check for 517,140.24 dollars.

But three and half months later, the manufacturer claimed it was all a big misunderstanding.

The company then fired off four letters and hired a collection agency as they sought to recoup 411,288.49 dollars, the amount it claimed Rodriguez was overpaid.

But she ignored Pfizer - so the company filed a lawsuit in Manhattan Supreme Court last week.

"By virtue of the fact that they bring this claim so late in the game, so long after their alleged mistake, [it] is just a cheap bullying tactic that we expect the court to see right through," New York Post quoted her lawyer, Saul Zabell as saying. (ANI)