Two towns in Bulgaria where new ski developments have attracted a large number of international property investors are opposing their inclusion on UNESCO's World Heritage List.

Bansko and Razlog on the edge of the UNESCO protected Pirin Mountain National Park are concerned that world heritage status, normally regarded as a powerful marketing tool to attract visitors and investment, would harm future development.

The towns have already been at loggerheads with green campaigners over the extent of their property development and European Union inspectors are due to investigate claims of illegal construction in the area.

Aleksandar Kravarov, mayor of the Bansko municipality, and Blagoy Dunkin, the acting mayor of the nearby municipality of Razlog, have written an open letter to Bulgarian Prime Minister Boyko Borisov in which they state their concerns.

Bansko has Bulgaria's largest winter resort of the same name. In recent years, it has witnessed a construction boom, which environmentalists say is taking place without regard to rules and regulations for the protection of the environment, and without assessment of the long-term benefit of the development.

The mayors claim that including them in the national park would mean a ban on all kinds of activities in the park including important infrastructure projects, the enlargement of the ski zones in Bankso and Dobrinishte, the construction of the ski and golf resort Kulinoto and the Struma highway.

Representatives of UNESCO's World Heritage Committee are currently carrying out inspections of territories around the Pirin National Park which is a World Heritage site.

'Over the years, the park's area has increased from 24,000 hectares to the current 40,000 hectares. Now, under pressure from ecological organisations, which have turned the protection of the environment into a personal lucrative business, UNESCO want an additional enlargement of 12,000 hectares,' the letter claims.

'In the current conditions of a global crisis, mountain tourism has an enormous importance for the survival, prosperity and the retention of jobs in all spheres of the national economy,' the letter points out. It concludes that the inclusion of the two towns in the park is unnecessary.

The towns though are also facing criticism from the European Commission. EU inspectors are due to start examining what it describes as 'ambitious' plans to construct new ski resorts in Bulgaria and also in Romania, Slovakia and the Ukraine which the World Wide Fund for Nature has described as seeking short term profits without regard to the long term impact in financial, environmental and social terms.

'There are all too many cases, especially in Bulgaria, for example in the Pirin and Rila National Parks, or in Vitosha Nature Park near Sofia, where ski areas have been or are being constructed illegally, in violation of national and in many cases EU legislation,' a recent report from the WWF claimed.