Museum bosses have vowed to try and retain a Roman tombstone being held at Preston's Museum of Lancashire.

The stone, which dates back more than 2000 years, is being dried out and cleaned at the Stanley Street museum following its discovery in Lancaster last week.

But the owner of the land it was found on, developer Christopher Tudor-Whelan, said he may have to sell the relic to recoup the costs of getting it out of the ground.

Edmund Southworth of the Lancashire County Museums Service said he would meet Mr Tudor-Whelan to discuss the alternatives available to him following speculation that it could fetch as much as £57,500 if sold through Sotheby's in New York.

He said: "This is a hugely significant find because of the excellent condition it is in. It would be a great shame to lose it. It should stay in a Lancashire museum."

The tombstone, which measures about 2.5m, is currently in pieces and could take five months to clean and restore.

It shows a mounted trooper, holding a sword and the head of a man he has just killed. An inscription gives the soldier's name as Lucius Nisus Vodvilleus. He is believed to have served with the Ala Augusta unit of the Roman Army.

Above his head is a face, believed to be that of the Medusa. The soldier's victim is kneeling at his feet, still holding his sword.

Mr Southworth said beheading war victims was a common practice but no such depiction of a man on horseback has been found before. He added: "This guy was obviously very important because he was buried away from others who were found ten years ago on an adjoining site."

Mr Tudor-Whelsan said: "I need to replace the costs it took me to get the tombstone out of the ground. If the museum service are willing to pay them to me then I'll be happy to give it to them."