The museum closed in November after its freight company – started to subsidise popular but expensive heritage train trips – collapsed, leaving more than $700,000 in debt.

Around 100 people gathered at the Kingston site to buy scrap metal, old carriages, memorabilia or to see the trains up close.

Heritage conservationist Chris Richards, who has been battling with liquidators Deloitte, told the crowd the sale was illegal and buyers could be potentially liable.

Security tried to remove Mr Richards from the yard but he refused to leave, moments later he and another man began arguing during an interview with The Canberra Times.

Mr Richards asked one of the liquidators why a bid from a benefactor to buy the railway museum, including its debts, was rejected.

The liquidator refused to answer before the two argued about the legality of the sale.

"If the other options are there, then why are we at auction today? You don't represent the bulk of the membership." Mr Richards said.

Before the spat, Mr Richards said most of the trains on site were heritage items.

"I believe the wrong thing is being done," Mr Richards said.

Mr Richards said Deloitte had failed to prove a root of title – a deed allowing the sale of the item – before beginning the auction.

Mr Richards provided emails which showed he told Deloitte some of the items on auction were approved for heritage listing by the ACT Heritage Council.

He also provided emails which showed he had contacted past or existing owners of auction items who were dismayed at the sale.

Meanwhile, Ben Greentree was purchasing old railway tracks and parts for Access Recycling, a scrap metal recycling plant.

"These rail lines here, they can be reused for line. Or they can be broken up and sold to a foundry. Or ... turned into new cars and those kind of things," Mr Greentree said.

Craig Prior waged a long bidding war with an unseen online bidder before purchasing a former sleeper carriage for $28,000.

"We're just gonna run 'em as part of the historical sites we run," Mr Prior said.

"It'll be on the rails, don't worry about that."

Mr Prior said he was the second last driver of one of the steam trains on the site when it was still run for revenue.