Campaigners hoping to save the traditional beam on a famous Co Down lighthouse fear the work will be carried out over Easter without further public consultation.
The St John’s Point structure at Killough dates back to 1839 and has a Fresnel lens lamp that projects a long-distance beam using a huge lens rotating inside a mercury bath.
Sinn Fein MLA Chris Hazzard is opposed to the fitting of a flashing LED light. He said: “The sweeping beam is a quintessential feature of the Down coastline. It should undoubtedly be preserved as a living, working symbol of our proud maritime heritage.”
The building is now the responsibility of the Commissioners of Irish Lights - a maritime safety organisation based in Dublin but with responsibility for lighthouses and other coastal infrastructure on both sides of the Irish border.
South Down MP, Margaret Ritchie, is also backing the campaign and has written to both British and Irish governments, asking them to intervene in an effort to save the traditional lamp.
The existing sweeping beam is visible up to 24 miles while the LED version has a reported range of up to 18 miles - which is still well within safety limits.
Over the years, the lamp’s light source was converted from oil to coal gas, to vaporised paraffin and eventually to electricity in 1981.