Romanian MPs have become embroiled in a row over the ownership of Bran Castle - the 14th-Century building famous for its links to the Count Dracula story.
Prince Vlad "the impaler" is thought to have stayed at Castle Bran
It was returned to New York architect Dominic Habsburg, a descendant of the country's former rulers, last year after 60 years under state control.
Some MPs say that process was illegal and want to stop the castle being sold.
Mr Habsburg has threatened legal action, saying it would be a "dreadful injustice" to strip him of ownership.
The infamous Prince Vlad "the impaler", the real-life inspiration for Dracula, is reputed to have spent a night at Castle Bran.
This connection has been a boon to the tourist industry in Romania, and MPs are keen to hold on to a prized asset.
Earlier this year, Mr Habsburg said he would be willing to sell it back to the Romanian authorities for $78m (£40m) - but ministers said the price was too high.
During a parliamentary debate this week, opposition MP Dumitru Ioan Puchianu said the return of the castle had been illegal because of procedural errors.
He said Mr Habsburg, whose family was thrown out of the castle after World War II, should not be allowed to sell it.
In response, Mr Habsburg issued a letter through his lawyers threatening to sue for damages of some $200m if the MPs stripped him of his right to sell the castle.
"I live once more with the feeling of dread in which I once lived, as a child, when my family and I were forced out of our home and thrown out into the streets in mid-winter," the letter said.
The castle rises dramatically from the forests in the foothills of the Carpathian mountains, 170km (105 miles) north of the capital Bucharest.
About 450,000 tourists are said to visit each year.