Unionised workers at one of Victoria's most popular tourist attractions are threatening to strike if their demands on pay and working conditions are not met.   

The union says protected industrial action will likely affect Sovereign Hill's operations during the inaugural King's Birthday long weekend, with a final decision on what action will be taken expected to be made on Thursday.

More than 82 per cent of union members have voted in favour of a strike of up to 24 hours unless management agrees to demands, which include an increased pay rise offer.

The Media Entertainment and Arts Alliance (MEAA), which is the union representing the workers, ran a protected-action ballot that closed last night. 

The union says negotiations with Sovereign Hill management over the enterprise bargaining agreement have reached a stalemate after an 11-month process. 

Staff to vote on offer 

Sovereign Hill is offering a 5 per cent pay rise in the first year and a 3.5 per cent increase in years two and three, with a one-off payment of $1,500 to provide relief from cost-of-living pressures. 

It says it is also offering new opportunities for training, flexibility and career progression. 

The MEAA is pushing for a higher pay rise in line with inflation, which is 6.8 per cent, the reinstatement of weekend penalty rates and a cap on the use of voluntary labour.  

Sovereign Hill management is putting its offer out to all staff to vote on tomorrow. 

MEAA acting director of entertainment, crew and sport section Nikau Irvine said management should halt the vote, withdraw the offer and sit down with union members to reach an agreement. 

"Refusal to reinstate penalty rates will continue to punish those who work on weekends.

"And the refusal to discuss volunteer engagement opens up the risk for management to make good on their threats to replace employees with volunteers."

'Irresponsible' to meet demands

Sovereign Hill chief executive Sara Quon said in a statement on Wednesday the not-for-profit business could not afford to pay demands from the MEAA, because it would threaten the organisation's ongoing viability. 

In a previous statement released last week, Ms Quon said the final request from the union bargaining group would amount to a nearly 30 per cent cost increase in year one, which would be "financially irresponsible to deliver". 

"Our entire workforce that is covered by enterprise bargaining is voting over the next week on our fair and generous pay and conditions offer," she said. 

MEAA union members at Sovereign Hill will meet on Wednesday and Thursday to consider their next steps. 

Not all Sovereign Hill workers are members of the union. 

The outcome of the all-staff enterprise bargaining vote will be decided on June 14 when voting closes. 

Sovereign Hill delivers an estimated $260 million of economic output to Victoria annually and $183 million to Ballarat, according to Ms Quon.

Sovereign Hill's workforce fluctuates between 250 and 350 staff depending on events or seasonal demands. 

About 200 volunteers also support the organisation.