Can my employer force me to work on a public holiday without extra pay?

Generally, yes. Under the Employment and Industrial Relations Act, Chapter 452 of the Laws of Malta, and the related regulations on public holidays, an employee required to work on a public holiday is typically entitled to be paid at an enhanced rate for that day, on top of their normal entitlement to the holiday itself, though the exact rate and mechanism can vary depending on the applicable wage regulation order for your specific sector, so the precise premium is worth confirming against the rules that apply to your industry. If you were paid only your standard daily rate for working on the public holiday, with no additional premium at all, this does appear inconsistent with the general entitlement, and you have a reasonable basis to raise the discrepancy with your employer. Request a written explanation of how your public holiday pay was calculated, referencing the specific wage regulation order or contractual provision they relied on. If the explanation doesn't hold up, or your employer simply made an error, you can file a complaint with the Department of Industrial and Employment Relations to have the correct payment enforced.