BUDAPEST (Reuters) - Workers at German carmaker Audi's plant in the Hungarian city of Gyor were to go on a two-hour warning strike on Friday as they try to force the company to narrow the wage gap between their salaries and those of Western and regional peers. Audi, a unit of Volkswagen group, has invested billions of euros in Hungary and operates one of its largest production facilities worldwide in the central European country. The Audi Hungaria Independent Union said it had rejected the most recent offer from the company, which was for a 10 percent wage increase now and another 10 percent in January 2020. The union, which represents 7,300 members out of more than 12,000 at the Hungarian plant, wants an immediate 18 percent raise and said it felt a 40 percent wage hike would allow its workers a decent standard of life. They said the company's Slovakian workers earn on average 28 percent more than Hungarians, Polish workers earn 39 percent more, and Belgian workers earn 3.6 times as much as they do. Audi said in a statement on Wednesday that current wages and the raise plan they offered were competitive and outstanding in Hungary. (Reporting by Marton Dunai; Editing by Alexandra Hudson)